Download as PDF, PPTX
![Origins: LISP & Smalltalk
“In Lisp, you don’t just write your
program down toward the language,
you also build the language up
toward your program”
- Paul Graham
“When [Smalltalk] is used to
describe an application system, the
developer extends Smalltalk,
creating a domain-specific language
by adding a new vocabulary of
language elements ...”
- Adele Goldberg
DSLs 2010 - 10
©ASERT2006-2010](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-10-2048.jpg)
![...Origins: Minilanguages
PowerPoint DSL for previous slide
import builder.PowerPointBuilder
def name = 'minilanguages'
assert new File("${name}.pic').exists()
"groff -e -p ${name}.pic > ${name}.ps".execute()
"gs -q -sDEVICE='ppmraw' -g2600x3500 -r300x300 -sOutputFile='-' -dBATCH ↵
–dNOPAUSE ${name}.ps | pnmcrop | ppmtogif > ${name}.gif".execute()
def builder = new PowerPointBuilder() // Adapted from Erik Pragt
builder.slideshow(filename: 'DSLsInGroovy_MiniLanguages.ppt') {
slide(title: 'Origins: Minilanguages...') {
image(
origin: [0, 15],
src: "${name}.gif",
caption: 'Source: The Art of Unix Programming:Taxonomy...' )
textbox(
origin: [5, 100],
text: new File("${name}.pic").text,
caption: 'Input DSL: pic for above picture' )
textbox(
origin: [115, 100],
text: new File("${name}.ps").text,
caption: 'Output "DSL": Postscript for above picture' )
}
}
DSLs 2010 - 12](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-12-2048.jpg)
![DSLs 2010 - 28
©ASERT2006-2010
Groovy Starter
System.out.println("Hello, World!"); // supports Java syntax
println 'Hello, World!' // but can remove some syntax
String name = 'Guillaume' // Explicit typing/awareness
println "$name, I'll get the car." // Gstring (interpolation)
def longer = """${name}, the car
is in the next row.""" // multi-line, implicit type
assert 0.5 == 1/2 // BigDecimal equals()
assert 0.1 + 0.2 == 0.3 // and arithmetic
def printSize(obj) { // implicit/duck typing
print obj?.size() // safe dereferencing
}
def pets = ['ant', 'bee', 'cat'] // native list syntax
pets.each { pet -> // closure support
assert pet < 'dog' // overloading '<' on String
} // or: for (pet in pets)...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-28-2048.jpg)
![A Better Java...
DSLs 2010 - 29
©ASERT2006-2010
import java.util.List;
import java.util.ArrayList;
class Erase {
private List removeLongerThan(List strings, int length) {
List result = new ArrayList();
for (int i = 0; i < strings.size(); i++) {
String s = (String) strings.get(i);
if (s.length() <= length) {
result.add(s);
}
}
return result;
}
public static void main(String[] args) {
List names = new ArrayList();
names.add("Ted"); names.add("Fred");
names.add("Jed"); names.add("Ned");
System.out.println(names);
Erase e = new Erase();
List shortNames = e.removeLongerThan(names, 3);
System.out.println(shortNames.size());
for (int i = 0; i < shortNames.size(); i++) {
String s = (String) shortNames.get(i);
System.out.println(s);
}
}
}
This code
is valid
Java and
valid Groovy
Based on an
example by
Jim Weirich
& Ted Leung](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-29-2048.jpg)
![...A Better Java...
DSLs 2010 - 30
©ASERT2006-2010
import java.util.List;
import java.util.ArrayList;
class Erase {
private List removeLongerThan(List strings, int length) {
List result = new ArrayList();
for (int i = 0; i < strings.size(); i++) {
String s = (String) strings.get(i);
if (s.length() <= length) {
result.add(s);
}
}
return result;
}
public static void main(String[] args) {
List names = new ArrayList();
names.add("Ted"); names.add("Fred");
names.add("Jed"); names.add("Ned");
System.out.println(names);
Erase e = new Erase();
List shortNames = e.removeLongerThan(names, 3);
System.out.println(shortNames.size());
for (int i = 0; i < shortNames.size(); i++) {
String s = (String) shortNames.get(i);
System.out.println(s);
}
}
}
Do the
semicolons
add anything?
And shouldn‟t
we us more
modern list
notation?
Why not
import common
libraries?](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-30-2048.jpg)
![...A Better Java...
DSLs 2010 - 31
©ASERT2006-2010
class Erase {
private List removeLongerThan(List strings, int length) {
List result = new ArrayList()
for (String s in strings) {
if (s.length() <= length) {
result.add(s)
}
}
return result
}
public static void main(String[] args) {
List names = new ArrayList()
names.add("Ted"); names.add("Fred")
names.add("Jed"); names.add("Ned")
System.out.println(names)
Erase e = new Erase()
List shortNames = e.removeLongerThan(names, 3)
System.out.println(shortNames.size())
for (String s in shortNames) {
System.out.println(s)
}
}
}](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-31-2048.jpg)
![...A Better Java...
DSLs 2010 - 32
©ASERT2006-2010
class Erase {
private List removeLongerThan(List strings, int length) {
List result = new ArrayList()
for (String s in strings) {
if (s.length() <= length) {
result.add(s)
}
}
return result
}
public static void main(String[] args) {
List names = new ArrayList()
names.add("Ted"); names.add("Fred")
names.add("Jed"); names.add("Ned")
System.out.println(names)
Erase e = new Erase()
List shortNames = e.removeLongerThan(names, 3)
System.out.println(shortNames.size())
for (String s in shortNames) {
System.out.println(s)
}
}
}
Do we need
the static types?
Must we always
have a main
method and
class definition?
How about
improved
consistency?](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-32-2048.jpg)
![...A Better Java...
DSLs 2010 - 35
©ASERT2006-2010
def removeLongerThan(strings, length) {
strings.findAll{ it.size() <= length }
}
names = ["Ted", "Fred", "Jed", "Ned"]
System.out.println(names)
shortNames = removeLongerThan(names, 3)
System.out.println(shortNames.size())
shortNames.each{ System.out.println(s) }](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-35-2048.jpg)
![...A Better Java...
DSLs 2010 - 36
©ASERT2006-2010
def removeLongerThan(strings, length) {
strings.findAll{ it.size() <= length }
}
names = ["Ted", "Fred", "Jed", "Ned"]
System.out.println(names)
shortNames = removeLongerThan(names, 3)
System.out.println(shortNames.size())
shortNames.each{ System.out.println(s) }
Is the method
now needed?
Easier ways to
use common
methods?
Are brackets
required here?](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-36-2048.jpg)
![...A Better Java...
DSLs 2010 - 37
©ASERT2006-2010
names = ["Ted", "Fred", "Jed", "Ned"]
println names
shortNames = names.findAll{ it.size() <= 3 }
println shortNames.size()
shortNames.each{ println it }](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-37-2048.jpg)
![...A Better Java
DSLs 2010 - 38
©ASERT2006-2010
names = ["Ted", "Fred", "Jed", "Ned"]
println names
shortNames = names.findAll{ it.size() <= 3 }
println shortNames.size()
shortNames.each{ println it }
["Ted", "Fred", "Jed", "Ned"]
3
Ted
Jed
Ned](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-38-2048.jpg)
![Grapes / Grab
DSLs 2010 - 39
©ASERT2006-2010
// Google Collections example
@Grab('com.google.collections:google-collections:1.0')
import com.google.common.collect.HashBiMap
HashBiMap fruit =
[grape:'purple', lemon:'yellow', lime:'green']
assert fruit.lemon == 'yellow'
assert fruit.inverse().yellow == 'lemon'](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-39-2048.jpg)
![...Testing DSLs: Spock...
©ASERT2006-2010
import com.gargoylesoftware.htmlunit.WebClient
import spock.lang.*
import org.junit.runner.RunWith
@Speck ()
@RunWith (Sputnik)
class TestSimpBlogSpock {
def page, subheadings, para, form, result
@Unroll("When #author posts a #category blog with content '#content' it sho
def "when creating a new blog entry"() {
given:
page = new WebClient().getPage('http://localhost:8080/postForm')
form = page.getFormByName('post')
when:
form.getInputByName('title').setValueAttribute("$author was here (and s
form.getSelectByName('category').getOptions().find { it.text == categor
form.getSelectByName('author').getOptions().find { it.text == author }.
form.getTextAreaByName('content').setText(content)
result = form.getInputByName('btnPost').click()
subheadings = result.getElementsByTagName('h3')
para = result.getByXPath('//TABLE//TR/TD/P')[0]
...
DSLs 2010 - 45](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-45-2048.jpg)
![... Testing DSLs: Spock
©ASERT2006-2010
...
then:
page.titleText == 'Welcome to SimpBlog'
result.getElementsByTagName('h1').item(0).textContent.matches("Post.*: $au
subheadings.item(1).textContent == "Category: $category"
subheadings.item(2).textContent == "Author: $author"
and:
para.textContent == content
where:
author << ['Bart', 'Homer', 'Lisa']
category << ['Home', 'Work', 'Food']
content << ['foo', 'bar', 'baz']
}
}
// Optional use of 'and:'
DSLs 2010 - 46](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-46-2048.jpg)
![Grails Bean Builder Example
DSLs 2010 - 54
©ASERT2006-2010
bb.beans {
marge(Person) {
name = "marge"
husband = { Person p ->
name = "homer"
age = 45
props = [overweight:true, height:"1.8m"]
}
children = [bart, lisa]
}
bart(Person) {
name = "Bart"
age = 11
}
lisa(Person) {
name = "Lisa"
age = 9
}
}
// source: 14. Grails and Spring: 14.3 Runtime Spring with the Beans DSL](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-54-2048.jpg)
![Static Imports...
DSLs 2010 - 60
©ASERT2006-2010
import groovy.swing.SwingXBuilder
import static java.awt.Color.*
import static java.lang.Math.*
def swing = new SwingXBuilder()
def frame = swing.frame(size: [300, 300]) {
graph(plots: [
[GREEN, {value -> sin(value)}],
[BLUE, {value -> cos(value)}],
[RED, {value -> tan(value)}]
])
}.show()
Java Static Imports
Discussed later:
Builders
Closures](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-60-2048.jpg)
![...Static Imports...
DSLs 2010 - 61
©ASERT2006-2010
import groovy.swing.SwingXBuilder
import static java.awt.Color.*
import static java.lang.Math.*
def swing = new SwingXBuilder()
def frame = swing.frame(size: [300, 300]) {
graph(plots: [
[GREEN, {value -> sin(value)}],
[BLUE, {value -> cos(value)}],
[RED, {value -> tan(value)}]
])
}.show()
Java gives us this](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-61-2048.jpg)
![...Static Imports...
DSLs 2010 - 62
©ASERT2006-2010
import groovy.swing.SwingXBuilder
import static java.awt.Color.*
import static java.lang.Math.*
def swing = new SwingXBuilder()
def frame = swing.frame(size: [300, 300]) {
graph(plots: [
[GREEN, {value -> sin(value)}],
[BLUE, {value -> cos(value)}],
[RED, {value -> tan(value)}]
])
}.show()
Java gives us this](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-62-2048.jpg)
![...Static Imports
DSLs 2010 - 64
©ASERT2006-2010
import groovy.swing.SwingXBuilder
import static java.lang.Math.*
import static java.awt.Color.GREEN as Lime
import static java.awt.Color.BLUE as Sky
import static java.awt.Color.RED as Maraschino
def swing = new SwingXBuilder()
def frame = swing.frame(size: [300, 300]) {
graph(plots: [
[Lime, {value -> sin(value)}],
[Sky, {value -> cos(value)}],
[Maraschino, {value -> tan(value)}]
])
}.show()
Java doesn‟t give us this!](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-64-2048.jpg)
![Literal Syntax Conventions
• Lists
– Special syntax for list literals
– Additional common methods (operator overloading)
• Maps
– Special syntax for map literals
– Additional common methods
• Ranges
– Special syntax for various kinds of ranges
DSLs 2010 - 65
©ASERT2006-2010
def list = [3, new Date(), 'Jan']
assert list + list == list * 2
def map = [a: 1, b: 2]
assert map['a'] == 1 && map.b == 2
def letters = 'a'..'z'
def numbers = 0..<10](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-65-2048.jpg)
![Literal Syntax Conventions in DSLs
DSLs 2010 - 66
©ASERT2006-2010
import static java.util.Calendar.getInstance as getNow
import static java.util.Calendar.*
def discount = [normal:0, silver:5, gold:10]
def roomrate = [weekday:150, weekend:95]
for (level in ['normal', 'silver', 'gold']) {
def multiplier = 1 - discount[level] / 100
print 'Your room rate is: '
if (now[DAY_OF_WEEK] in MONDAY..FRIDAY)
println roomrate.weekday * multiplier
else
println roomrate.weekend * multiplier
}
Your room rate is: 150
Your room rate is: 142.50
Your room rate is: 135.0
Literal list & map syntax
Ranges
Also
Static import aliases
BigDecimal arithmetic](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-66-2048.jpg)
![Compact Syntax...
• Java
• Groovy
DSLs 2010 - 67
©ASERT2006-2010
public class BuySharesJava {
public static void buyShares(int qty, String name) {
// business logic here ...
System.out.println("buying " + qty
+ " shares of " + name);
}
public static void main(String[] args) {
buyShares(3, "BHP");
}
}
def buyShares(qty, name) {
// business logic here ...
println "buying $qty shares of $name"
}
buyShares 3, 'BHP'
Script syntax
Conventions for visibility
GDK methods: println
Implicit typing
GString interpolation
Optional brackets & „;‟](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-67-2048.jpg)
![...Compact Syntax...
• Java
• Groovy
DSLs 2010 - 68
©ASERT2006-2010
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
public class ProcessCustomerJava {
public static void printDetails(Map<String, String> cust) {
System.out.println("Details as at: " + new Date());
String first = cust.get("first");
System.out.println("First name: " + first);
String last = cust.get("last");
System.out.println("Last name: " + (last != null ? last : "unknown"));
}
public static void main(String[] args) {
Map<String, String> details = new HashMap<String, String>();
details.put("first", "John");
details.put("last", "Smith");
printDetails(details);
}
} def printDetails(cust) {
println """Details as at: ${new Date()}
First name: $cust.first
Last name: ${cust.last ?: 'unknown'}"""
}
printDetails first: 'John', last: 'Smith'
Script syntax, Named params, Extra imports
Conventions for visibility, GDK methods
Implicit typing, Multi-line GString
Elvis operator, Optional brackets & „;‟](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-68-2048.jpg)
![...Compact Syntax
• Java
• Groovy
DSLs 2010 - 69
©ASERT2006-2010
import java.util.Date;
public class ProcessStrongCustomerJava {
public static void printDetails(CustomerJ cust) {
System.out.println("Details as at: " + new Date());
String first = cust.getFirst();
System.out.println("First name: " + first);
String last = cust.getLast();
System.out.println("Last name: " + (last != null ? last : "unknown"));
}
public static void main(String[] args) {
CustomerJ c = new CustomerJ();
c.setFirst("John");
c.setLast("Smith");
printDetails(c);
}
}
class CustomerJ {
private String first;
private String last;
public String getFirst() {
return first;
}
public void setFirst(String first) {
this.first = first;
}
public String getLast() {
return last;
}
public void setLast(String last) {
this.last = last;
}
}
class CustomerG { String first, last }
def printDetails(cust) {
println """Details as at: ${new Date()}
First name: $cust.first
Last name: ${cust.last ?: 'unknown'}"""
}
printDetails new CustomerG(first: 'John',
last: 'Smith')
Plus:
Named params for constructors
JavaBean conventions
Leverage Duck Typing](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-69-2048.jpg)
![Using With Example
DSLs 2010 - 70
©ASERT2006-2010
letters = ['a', 'b', 'c']
range = 'b'..'d'
letters.with {
add 'd'
remove 'a'
}
assert letters == range
map = [a:10, b:4, c:7]
map.with {
assert (a + b) / c == 2
}
Just normal methods
for ArrayList here](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-70-2048.jpg)
![Closures in DSLs...
DSLs 2010 - 78
©ASERT2006-2010
import static java.util.Calendar.*
def cart1 = [
[qty: 3, unitPrice: 50.0, gift: true,
name: 'Groovy in Action Book'],
[qty: 1, unitPrice: 40.0, gift: false,
name: 'Grails in Action eBook'],
[qty: 2, unitPrice: 25.0, gift: true,
name: 'Avatar DVD']
]
def cart2 = [
[qty: 1, unitPrice: 50.0, gift: true,
name: 'Groovy in Action Book'],
[qty: 2, unitPrice: 30.0, gift: false,
name: 'Avatar 3D DVD']
]
// ...
Nothing special here.
Just a list of maps.](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-78-2048.jpg)
![... Closures in DSLs
DSLs 2010 - 81
©ASERT2006-2010
// ...
def specials = [noDiscount, tenPercentOffAll,
tenPercentOffGifts, tenPercentOffOverForty,
tenPercentOffBooks, tenPercentOffDVDs,
buyThreeGetOneFree]
[
SUNDAY..SATURDAY,
[cart1, cart2]
].combinations().each { day, cart ->
printf "%d %2.2fn", day,
cart.sum(specials[day-1])
}
1 240.00
2 216.00
3 220.00
4 225.00
5 221.00
6 235.00
7 190.00
1 110.00
2 99.00
3 105.00
4 105.00
5 105.00
6 104.00
7 110.00](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-81-2048.jpg)
![©ASERT2006-2010
Better Control Structures: Switch Poker…
suits = 'SHDC'
ranks = '23456789TJQKA'
suit = { String card -> suits.indexOf(card[1]) }
rank = { String card -> ranks.indexOf(card[0]) }
rankSizes = { List cards ->
cards.groupBy(rank).collect{ k, v -> v.size() }.sort() }
rankValues = { List cards ->
cards.collect{ rank(it) }.sort() }
// ...
8C TS KC 9H 4S 7D 2S 5D 3S AC
hand1 hand2
println rankSizes(["7S", "7H", "2H", "7D", "AH"])
// => [1, 1, 3]
DSLs 2010 - 84](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-84-2048.jpg)
![©ASERT2006-2010
…Better Control Structures: Switch Poker…
// ...
flush = { List cards -> cards.groupBy(suit).size() == 1 }
straight = { def v = rankValues(it); v == v[0]..v[0]+4 }
straightFlush = { List cards -> straight(cards) && flush(cards)
}
fourOfAKind = { List cards -> rankSizes(cards) == [1, 4] }
fullHouse = { List cards -> rankSizes(cards) == [2, 3] }
threeOfAKind = { List cards -> rankSizes(cards) == [1, 1, 3] }
twoPair = { List cards -> rankSizes(cards) == [1, 2, 2] }
pair = { List cards -> rankSizes(cards) == [1, 1, 1, 2] }
// ...
DSLs 2010 - 85](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-85-2048.jpg)
![Type Transformation Example
DSLs 2010 - 87
©ASERT2006-2010
class InventoryItem {
def weight, name
InventoryItem(Map m) {
this.weight = m.weight; this.name = m.name
}
InventoryItem(weight, name) {
this.weight = weight; this.name = name
}
InventoryItem(String s) {
s.find(/weight=(d*)/) { all, w -> this.weight = w }
s.find(/name=(.*)/) { all, n -> this.name = n }
}
}
def room = [:]
def gold = [weight:50, name:'Gold'] as InventoryItem
def emerald = [10, 'Emerald'] as InventoryItem
def dagger = ['weight=5, name=Dagger'] as InventoryItem
room.contents = [gold, emerald, dagger]
room.contents.each{ println it.dump() }](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-87-2048.jpg)
![...Builders…
DSLs 2010 - 91
©ASERT2006-2010
def colors = ['red','darkOrange','blue','darkGreen']
(0..3).each { index ->
star( cx: 50 + (index*110), cy: 50, or: 40, ir: 15,
borderColor: 'black', count: 2+index, fill: colors[index] )
star( cx: 50 + (index*110), cy: 140, or: 40, ir: 15,
borderColor: 'black‘, count: 7+index, fill: colors[index] )
}
• GraphicsBuilder](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-91-2048.jpg)
![…Builders
new AntBuilder().with {
echo(file:'Temp.java', '''
class Temp {
public static void main(String[] args) {
System.out.println("Hello");
}
}
''')
javac(srcdir:'.', includes:'Temp.java', fork:'true')
java(classpath:'.', classname:'Temp', fork:'true')
echo('Done')
}
// =>
// [javac] Compiling 1 source file
// [java] Hello
// [echo] Done
©ASERT2006-2010
DSLs 2010 - 92](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-92-2048.jpg)
![DSLs 2010 - 94
©ASERT2006-2010
ExpandoMetaClass…
import static java.lang.Character.isUpperCase
String.metaClass.swapCase = {
delegate.collect { ch ->
isUpperCase(ch as char) ?
ch.toLowerCase() :
ch.toUpperCase()
}.join()
}
println new Date().toString().swapCase()
// => sUN nOV 09 17:30:06 est 2008
List.metaClass.sizeDoubled = {-> delegate.size() * 2 }
LinkedList list = []
list << 1
list << 2
assert 4 == list.sizeDoubled()](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-94-2048.jpg)
![...EMC Neo4j DSL…
DSLs 2010 - 98
©ASERT2006-2010
@GrabResolver(name= 'neo4j-public-repo', root= 'http://m2.neo4j.org')
@Grab('org.neo4j:neo4j-kernel:1.1.1')
import org.neo4j.kernel.EmbeddedGraphDatabase
import org.neo4j.graphdb.*
// an enum helper
enum MyRelationships implements RelationshipType { knows }
// some optional syntactic sugar using EMC DSL
Node.metaClass {
propertyMissing { String name, val ->
delegate.setProperty(name, val) }
propertyMissing { String name -> delegate.getProperty(name) }
methodMissing { String name, args ->
delegate.createRelationshipTo(args[0], MyRelationships."$name") }
}
Relationship.metaClass {
propertyMissing { String name, val ->
delegate.setProperty(name, val) }
propertyMissing { String name -> delegate.getProperty(name) }
}
// ...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-98-2048.jpg)
![Game example...
DSLs 2010 - 100
©ASERT2006-2010
// Trying out the game DSL idea by Sten Anderson from:
// http://blogs.citytechinc.com/sanderson/?p=92
class GameUtils {
static VOWELS = ['a', 'e', 'i', 'o', 'u']
static listItems(things) {
def result = ''
things.eachWithIndex{ thing, index ->
if (index > 0) {
if (index == things.size() - 1) result += ' and '
else if (index < things.size() - 1) result += ', '
}
result += "${thing.toLowerCase()[0] in VOWELS ? 'an' : 'a'} $thing
}
result ?: 'nothing'
}
}
import static GameUtils.*
...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-100-2048.jpg)
![...Game example...
DSLs 2010 - 101
©ASERT2006-2010
...
class Room {
def description
def contents = []
}
...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-101-2048.jpg)
![...Game example...
DSLs 2010 - 102
©ASERT2006-2010
...
class Player {
def currentRoom
def inventory = []
void look() {
println "You are in ${currentRoom?.description?:'the void'}
which contains ${listItems(currentRoom?.contents)}"
}
void inv() {
println "You are holding ${listItems(inventory)}"
}
void take(item) {
if (currentRoom?.contents?.remove(item)) {
inventory << item
println "You took the $item"
} else {
println "I see no $item here"
}
}
...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-102-2048.jpg)
![...Game example...
DSLs 2010 - 104
©ASERT2006-2010
...
Room plainRoom = new Room(description:'a plain white room',
contents:['dagger', 'emerald', 'key'])
Player player = new Player(currentRoom:plainRoom)
player.with {
inv
look
take dagger
inv
look
take emerald
inv
look
take key
drop emerald
inv
look
}
assert player.inventory == ['dagger', 'key']
...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-104-2048.jpg)
) }
show = { thing -> [thing, { println it }] }
square_root = { Math.sqrt(it) }
given = { it }
given 100 please show the square_root
// ==> 10.0](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-106-2048.jpg)
) }
Object.metaClass.the =
{ clos -> [delegate[0], clos] }
show = [{ println it }]
square_root = { Math.sqrt(it) }
please = { it }
please show the square_root of 100
// ==> 10.0](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-107-2048.jpg)
![...GEP3 example...
DSLs 2010 - 108
©ASERT2006-2010
show = { println it }
square_root = { Math.sqrt(it) }
def please(action) {
[the: { what ->
[of: { n -> action(what(n)) }]
}]
}
please show the square_root of 100
// ==> 10.0
Inspiration for this example came from …](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-108-2048.jpg)
![…Medical Prescription DSL…
DSLs 2010 - 112
©ASERT2006-2010
// ...
// ---- DSL implementation ------------------------------
Integer.metaClass.getHour = {-> 1.hours }
Integer.metaClass.getPill = {-> 1.pills }
Integer.metaClass.getHours = {-> new Duration(number: delegate,
unit: 'hour', units: 'hours') }
Integer.metaClass.getPills = {-> new Quantity(number: delegate,
unit: 'pill', units: 'pills') }
// use the script binding for storing new drugs available as variables
binding = new Binding() {
def getVariable(String drug) {
new Drug(name: drug)
}
}
take = {Quantity quantity ->
['of': {Drug drug ->
['after': {Duration duration ->
println "Take $quantity of $drug afer $duration"
}]
}]
}
// ...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-112-2048.jpg)
![©ASERT2006-2010
…EasyB
• Description: BDD, Rspec-like testing library
examples "The number #{number}' should be converted to #{romanNumerals}", {
number = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
romanNumerals = ["I", "II", "III", "IV", "V",
"VI", "VII", "VIII", "IX", "X"]
}
scenario "Converting #number into the roman numeral #romanNumerals", {
given "the number #number", {
theNumber = number
}
when "the system converts this number to the roman numeral equivalent", {
theConvertedNumber = RomanNumerals.fromInteger(theNumber)
}
then "the result should be #romanNumerals", {
theConvertedNumber.shouldBe romanNumerals
}
}
DSLs 2010 - 122
Source: http://www.wakaleo.com/blog/285-example-driven-testing-with-easyb](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-122-2048.jpg)
![...EasyB Preprocessing...
String addCommas(text) {
def pattern =
~/(.*)(given|when|then) "([^"]*(.[^"]*)*)" {(.*)/
def replacement = /$1$2 "$3", {$4/
(text =~ pattern).replaceAll(replacement)
}
Source: http://hamletdarcy.blogspot.com/2010/02/groovy-antlr-plugins-for-better-dsls.html
DSLs 2010 - 124
Adds the comma in where required before Groovy sees it.](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-124-2048.jpg)
![GParsec...
• Miniature parsers
• Parser Combinators
def isLetter = { ch -> return Character.isLetter(ch) }
def isDigit = { ch -> return Character.isDigit(ch) }
def letter = satisfyC(isLetter)
def digit = satisfyC(isDigit)
def letterAndDigit = seqC(letter, digit)
assert letterAndDigit('a123###') == ['a', '1']
def identifier = seqC(identifierStart,
noneOrMoreC(identifierRest))
DSLs 2010 - 126](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-126-2048.jpg)
![... Currency DSL
DSLs 2010 - 137
©ASERT2006-2010
class CoinValues {
static get(Integer self, String name) {
self * Coin."${singular(name)}".value
}
static singular(String val) {
val.endsWith('ies') ? val[0..-4] + 'y' : val.endsWith('s') ? val[0..-2] : val
}
}
use (CoinValues) {
assert 2.quarters + 1.nickel + 2.pennies == 57
}
// EMC equivalent
Integer.metaClass.getProperty = { String name ->
def mp = Integer.metaClass.getMetaProperty(name)
if (mp) return mp.getProperty(delegate)
def singular = name.endsWith('ies') ? name[0..-4] + 'y' :
name.endsWith('s') ? name[0..-2] : name
delegate * Coin."$singular".value
}
assert 2.quarters + 1.nickel + 2.pennies == 57](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-137-2048.jpg)
![… Business logic DSL …
DSLs 2010 - 144
©ASERT2006-2010
class CustomerShell {
Object evaluate(String text) {
try {
def loader = new CustomerClassLoader()
def clazz = loader.parseClass(text)
def script = clazz.newInstance()
return script.run()
} catch (...) { ... }
}
}
class CustomerClassLoader extends GroovyClassLoader {
def createCompilationUnit(CompilerConfiguration config, CodeSource codeSource) {
CompilationUnit cu = super.createCompilationUnit(config, codeSource)
cu.addPhaseOperation(new CustomerFilteringNodeOperation(), Phases.SEMANTIC_ANALYSIS)
return cu
}
}
private class CustomerFilteringNodeOperation extends PrimaryClassNodeOperation {
// ...
private static final allowedStaticImports = [Math].asImmutable()
void visitStaticMethodCallExpression(StaticMethodCallExpression smce) {
if (!allowedStaticImports.contains(smce.ownerType.getTypeClass())) {
throw new SecurityException("Static method call expressions forbidden in acme shell.")
}
}
void visitWhileLoop(WhileStatement whileStatement) {
throw new SecurityException("While statements forbidden in acme shell.")
}
// ...
}
Please also see the ArithmeticShell which is included under examples in the Groovy distribution](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-144-2048.jpg)
![…Stock Exchange Order DSL…
DSLs 2010 - 150
©ASERT2006-2010
class Order {
def security
def quantity
def limitPrice
def allOrNone
def value
def bs
def buy(securityQuantity, closure) {
bs = 'Bought'
buySell(securityQuantity, closure)
}
def sell(securityQuantity, closure) {
bs = 'Sold'
buySell(securityQuantity, closure)
}
private buySell(securityQuantity, closure) {
// multiple assignment
(security, quantity) = [securityQuantity.security, securityQuantity.quantity]
// better clone the closure to avoid multi-threading access issues
def c = closure.clone()
// delegate the method calls inside the closure to our methodMissing
c.delegationStrategy = Closure.DELEGATE_ONLY
c.delegate = this
def valuation = c()
println "$bs $quantity $security.name at valuation of $valuation"
}
// methods inside the closure will assign the Order properties
def methodMissing(String name, args) {
this."$name" = args[0]
}
...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-150-2048.jpg)
![…Stock Exchange Order DSL…
DSLs 2010 - 153
©ASERT2006-2010
class Order {
...
def allOrNone
def valueCalculation
def bs
...
private buySell(securityQuantity,
closure) {
...
valueCalculation = c()
// debug print resulting order
println toString()
return this
}
...
def valueAs(Closure wrapee) {
// in order to be able to define closures like { qty * unitPrice } without having
// to explicitly pass the parameters to the closure we can wrap the closure inside
// another one and that closure sets a delegate to the qty and unitPrice variables
def wrapped = { qty, unitPrice ->
def cloned = wrapee.clone()
cloned.resolveStrategy = Closure.DELEGATE_ONLY
cloned.delegate = [qty: qty, unitPrice: unitPrice]
cloned()
}
return wrapped
}
String toString() {
"$bs $quantity shares of $security.name and valuation of
${valueCalculation(quantity, limitPrice)}"
}
}
newOrder.to.buy(100.shares.of(IBM)) {
limitPrice 300
allOrNone true
valueAs { qty * unitPrice - 500 }
}
newOrder.to.sell 200.shares.of(GOOG), {
limitPrice 200
allOrNone false
valueAs { qty * unitPrice - 100 }
}](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-153-2048.jpg)
![…Stock Exchange Order DSL…
DSLs 2010 - 155
©ASERT2006-2010
// Characteristics of the order: "of GOOG {...}"
def of(SecurityAndCharacteristics secAndCharact) {
security = secAndCharact.security
def c = secAndCharact.characteristics.clone()
c.delegationStrategy = Closure.DELEGATE_ONLY
c.delegate = this
c()
// debug print of the resulting order
println toString()
return this
}
// Valuation closure: "of { qty, unitPrice -> ... }"
def of(Closure valueCalculation) {
// in order to be able to define closures like { qty * unitPrice }
// without having to explicitly pass the parameters to the closure
// we can wrap the closure inside another one
// and that closure sets a delegate to the qty and unitPrice variables
def wrapped = { qty, unitPrice ->
def cloned = valueCalculation.clone()
cloned.resolveStrategy = Closure.DELEGATE_ONLY
cloned.delegate = [qty: qty, unitPrice: unitPrice]
cloned()
}
return wrapped
}
String toString() {
"$action $quantity shares of $security.name at limit price of $limitPrice"
}
}
// ...
http://groovyconsole.appspot.com/script/226001 by glaforge](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-155-2048.jpg)
![…Stock Exchange Order DSL…
DSLs 2010 - 156
©ASERT2006-2010
// ...
class Security {
String name
}
class SecurityAndCharacteristics {
Security security
Closure characteristics
}
class CustomBinding extends Binding {
def getVariable(String word) {
// return System.out when the script requests to write to 'out'
if (word == "out") System.out
// don't thrown an exception and return null
// when a silent sentence word is used,
// like "to" and "the" in our DSL
null
}
}
// Script helper method for "GOOG {}", "VMW {}", etc.
def methodMissing(String name, args) {
new SecurityAndCharacteristics(
security: new Security(name: name),
characteristics: args[0]
)
}
// Script helper method to make "order to" silent
// by just creating our current order
def order(to) { new Order() }
// use the script binding for silent sentence words like "to", "the"
binding = new CustomBinding()
// syntax for 200.shares
Integer.metaClass.getShares = { -> delegate }](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-156-2048.jpg)
![Einstein‟s Riddle : Prolog
©ASERT2006-2010
% from http://www.baptiste-wicht.com/2010/09/solve-einsteins-riddle-using-prolog
% Preliminary definitions
persons(0, []) :- !.
persons(N, [(_Men,_Color,_Drink,_Smoke,_Animal)|T]) :- N1 is N-1, persons(N1,T).
person(1, [H|_], H) :- !.
person(N, [_|T], R) :- N1 is N-1, person(N1, T, R).
% The Brit lives in a red house
hint1([(brit,red,_, _, _)|_]).
hint1([_|T]) :- hint1(T).
% The Swede keeps dogs as pets
hint2([(swede,_,_,_,dog)|_]).
hint2([_|T]) :- hint2(T).
% The Dane drinks tea
hint3([(dane,_,tea,_,_)|_]).
hint3([_|T]) :- hint3(T).
% The Green house is on the left of the White house
hint4([(_,green,_,_,_),(_,white,_,_,_)|_]).
hint4([_|T]) :- hint4(T).
% The owner of the Green house drinks coffee.
hint5([(_,green,coffee,_,_)|_]).
hint5([_|T]) :- hint5(T).
...
DSLs 2010 - 163](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-163-2048.jpg)
![Einstein‟s Riddle : Polyglot w/ DSL…
©ASERT2006-2010
// define some domain classes and objects
enum Pet { dog, cat, bird, fish, horse }
enum Color { green, white, red, blue, yellow }
enum Smoke { dunhill, blends, pallmall, prince, bluemaster }
enum Drink { water, tea, milk, coffee, beer }
enum Nationality { Norwegian, Dane, Brit, German, Swede }
dogs = dog; birds = bird; cats = cat; horses = horse
a = owner = house = the = abode = person = man = is = to =
side = next = who = different = 'ignored'
DSLs 2010 - 167
// some preliminary definitions
p = ProverFactory.prover
hintNum = 1
p.addTheory('''
persons(0, []) :- !.
persons(N, [(_Men,_Color,_Drink,_Smoke,_Animal)|T]) :- N1 is N-1, persons(N1,T).
person(1, [H|_], H) :- !.
person(N, [_|T], R) :- N1 is N-1, person(N1, T, R).
''')](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-167-2048.jpg)
![…Einstein‟s Riddle : Polyglot w/ DSL…
©ASERT2006-2010
DSLs 2010 - 168
// define some helper methods (our interface to prolog)
def addPairHint(Map m) {
def from = m.from?.toString()?.toLowerCase()
p.addTheory("""
hint$hintNum([(${from ?: '_'},${m.color ?: '_'},${m.drink ?: '_'},${m.smoke ?:
'_'},${m.pet ?: '_'})|_]).
hint$hintNum([_|T]) :- hint$hintNum(T).
""")
hintNum++
}
def addPositionHint(Map m, int pos) {
def from = m.from?.toString()?.toLowerCase()
p.addTheory("""
hint$hintNum(Persons) :- person($pos, Persons, (${from ?: '_'},${m.color ?:
'_'},${m.drink ?: '_'},${m.smoke ?: '_'},${m.pet ?: '_'})).
""")
hintNum++
}
def addToLeftHint(Map left, Map right) {
p.addTheory("""
hint$hintNum([(_,$left.color,_,_,_),(_,$right.color,_,_,_)|_]).
hint$hintNum([_|T]) :- hint$hintNum(T).
""")
hintNum++
}
...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-168-2048.jpg)
![…Einstein‟s Riddle : Polyglot w/ DSL…
©ASERT2006-2010
DSLs 2010 - 169
// now implement DSL in terms of helper methods
def the(Nationality n) {
def ctx = [from:n]
[
drinks: { d -> addPairHint(ctx + [drink:d]) },
smokes: { s -> addPairHint(ctx + [smoke:s]) },
keeps: { p -> addPairHint(ctx + [pet:p]) },
rears: { p -> addPairHint(ctx + [pet:p]) },
owns:{ _the -> [first:{ house -> addPositionHint(ctx, 1) }] },
has:{ _a ->
[pet: { a -> addPairHint(ctx + [pet:a]) }] +
Color.values().collectEntries{ c ->
[c.toString(), { _dummy -> addPairHint(ctx + [color:c]) } ]
}
},
lives: { _next -> [to: { _the ->
Color.values().collectEntries{ c ->
[c.toString(), { _dummy -> addNeighbourHint(ctx, [color:c]) } ]
}
}]}
]
}
...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-169-2048.jpg)
![…Einstein‟s Riddle : Polyglot w/ DSL…
©ASERT2006-2010
DSLs 2010 - 172
// now implement DSL in terms of helper methods
def the(Nationality n) {
def ctx = [from:n]
[
drinks: { d -> addPairHint(ctx + [drink:d]) },
smokes: { s -> addPairHint(ctx + [smoke:s]) },
keeps: { p -> addPairHint(ctx + [pet:p]) },
...
]
}
...
the German smokes prince
the(German).smokes(prince)
n = German
ctx = [from: German]
[drinks: …,
smokes: { s -> addPairHint([from: German, smoke: s]) },
keeps: …,
…
]
addPairHint([from: German, smoke: prince])](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-172-2048.jpg)
![…Einstein‟s Riddle : Polyglot w/ DSL
©ASERT2006-2010
DSLs 2010 - 174
class HousePlaceHolder {
def c1, script
def house(_is) {
[on: { _the -> [left: { _side -> [of: { __the ->
Color.values().collectEntries { c2 ->
[c2.toString(), { _dummy -> script.addToLeftHint(
[color: c1], [color: c2] )}]}
}]}]}]
}
}
def the(Color c1) { new HousePlaceHolder(c1:c1, script:this) }
def the(Color c1) {[
house: { _is -> [on: { _the -> [left: { _side -> [of: { __the ->
Color.values().collectEntries{ c2 -> [c2.toString(), { _dummy ->
addToLeftHint([color:c1], [color:c2])
}]}
}]}]}]}
]}
„house‟ is now understood](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-174-2048.jpg)
![Einstein‟s Riddle : Choco w/ DSL…
©ASERT2006-2010
DSLs 2010 - 176
@GrabResolver('http://www.emn.fr/z-info/choco-solver/mvn/repository/')
@Grab('choco:choco:2.1.1-SNAPSHOT')
import static choco.Choco.*
import choco.kernel.model.variables.integer.*
def m = new choco.cp.model.CPModel()
m.metaClass.plus = { m.addConstraint(it); m }
def s = new choco.cp.solver.CPSolver()
choco.Choco.metaClass.static.eq = { c, v -> delegate.eq(c, v.ordinal()) }
def makeEnumVar(st, arr) { choco.Choco.makeIntVar(st, 0, arr.size()-1,
choco.Options.V_ENUM) }
pets = new IntegerVariable[num]
colors = new IntegerVariable[num]
smokes = new IntegerVariable[num]
drinks = new IntegerVariable[num]
nations = new IntegerVariable[num]
(0..<num).each { i ->
pets[i] = makeEnumVar("pet$i", pets)
colors[i] = makeEnumVar("color$i", colors)
smokes[i] = makeEnumVar("smoke$i", smokes)
drinks[i] = makeEnumVar("drink$i", drinks)
nations[i] = makeEnumVar("nation$i", nations)
}
...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-176-2048.jpg)
![…Einstein‟s Riddle : Choco w/ DSL…
©ASERT2006-2010
DSLs 2010 - 177
// define DSL (simplistic non-refactored version)
def neighbours(var1, val1, var2, val2) {
and(
ifOnlyIf(eq(var1[0], val1), eq(var2[1], val2)),
implies(eq(var1[1], val1), or(eq(var2[0], val2), eq(var2[2], val2))),
implies(eq(var1[2], val1), or(eq(var2[1], val2), eq(var2[3], val2))),
implies(eq(var1[3], val1), or(eq(var2[2], val2), eq(var2[4], val2))),
ifOnlyIf(eq(var1[4], val1), eq(var2[3], val2))
)
}
iff = { e1, c1, e2, c2 -> and(*(0..<num).collect{
ifOnlyIf(eq(e1[it], c1), eq(e2[it], c2))
}) }
...
// define the DSL in terms of DSL implementation
def the(Nationality n) {
def ctx = [nations, n]
[
drinks:iff.curry(*ctx, drinks),
smokes:iff.curry(*ctx, smokes),
keeps:iff.curry(*ctx, pets),
rears:iff.curry(*ctx, pets),
owns:{ _the -> [first:{ house -> eq(nations[first], n)}] },
...](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-177-2048.jpg)
![…Einstein‟s Riddle : Choco w/ DSL
• Output:
DSLs 2010 - 179
©ASERT2006-2010
def pretty(s, c, arr, i) { c.values().find{
it.ordinal() == s.getVar(arr[i])?.value } }
// invoke logic solver
s.read(m)
def more = s.solve()
while (more) {
for (i in 0..<num) {
print 'The ' + pretty(s, Nationality, nations, i)
print ' has a pet ' + pretty(s, Pet, pets, i)
print ' smokes ' + pretty(s, Smoke, smokes, i)
print ' drinks ' + pretty(s, Drink, drinks, i)
println ' and lives in a ' + pretty(s, Color, colors, i) + ' house'
}
more = s.nextSolution()
}
Solving Einstein's Riddle:
The Norwegian has a pet cat smokes dunhill drinks water and lives in a yellow house
The Dane has a pet horse smokes blends drinks tea and lives in a blue house
The Brit has a pet bird smokes pallmall drinks milk and lives in a red house
The German has a pet fish smokes prince drinks coffee and lives in a green house
The Swede has a pet dog smokes bluemaster drinks beer and lives in a white house](https://image.slidesharecdn.com/groovydslpaulkingguillaumelaforgeoct2010-101107151609-phpapp01/75/groovy-DSLs-from-beginner-to-expert-179-2048.jpg)
Uploaded byPaul King
groovy DSLs from beginner to expert
The document discusses Domain-Specific Languages (DSLs), highlighting their features, advantages, and disadvantages compared to general-purpose programming languages. It explores the historical context of DSLs, their implementation patterns, and the Groovy programming language as a powerful tool for creating DSLs. The presentation aims to emphasize the importance of DSLs in improving communication between developers and domain experts, as well as enhancing code readability and maintainability.
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groovy DSLs from beginner to expert
- 1. Chicago, October 19- 22, 2010 Paul King @paulk_asert Groovy Committer ASERT, Australia Groovy.DSLs(from: beginner, to: expert) Guillaume Laforge @glaforge Groovy Project Manager SpringSource / VMWare
- 2. Topics Introduction • Groovy DSLFeatures • A Week In The Life Of DSL INC • Summary • More Info DSLs 2010 - 2 ©ASERT2006-2010
- 3. What is aDSL? • A domain-specific language is a programming language or executable specification language that offers, through appropriate notations and abstractions, expressive power focused on, and usually restricted to, a particular problem domain – In contrast, general-purpose languages are created to solve problems in many domains – Somewhere between declarative data and a full blown general- purpose programming language (GPL) – AKA: fluent / human interfaces, language oriented programming, problem-oriented languages, little / mini languages, macros, business natural languages Sources: http://en.wikipedia.org/wiki/Domain-specific_language van Deursen, A., Klint, P., Visser, J.: Domain-specific languages: an annotated bibliography. ACM SIGPLAN Notices 35 (2000) 26–36 ©ASERT2006-2010
- 4. 1. e4 e5 2.Nf3 Nc6 3. Bb5 a6
- 5. L2 U F-1B L2 F B -1 U L2
- 6.
- 7. Technical Examples Source: Applyingminilanguages: http://www.faqs.org/docs/artu/ch08s02.html <?xml version="1.0"?> <xsl:stylesheetversion="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="xml"/> <xsl:template match="*"> <xsl:element name="{name()}"> <xsl:for-each select="@*"> <xsl:element name="{name()}"> <xsl:value-of select="."/> </xsl:element> </xsl:for-each> <xsl:apply-templates select="*|text()"/> </xsl:element> </xsl:template> </xsl:stylesheet> cat thesis.ms | chem | tbl | refer | grap | pic | eqn | groff -Tps > thesis.ps <?xml version="1.0"?> <GTK-Interface> <widget> <class>GtkWindow</class> <name>HelloWindow</name> <border_width>5</border_width> <Signal> <name>destroy</name> <handler>gtk_main_quit</handler> </Signal> <title>Hello</title> <type>GTK_WINDOW_TOPLEVEL</type> <position>GTK_WIN_POS_NONE</position> <allow_shrink>True</allow_shrink> <allow_grow>True</allow_grow> <auto_shrink>False</auto_shrink> <widget> <class>GtkButton</class> <name>Hello World</name> <can_focus>True</can_focus> <label>Hello World</label> </widget> </widget> </GTK-Interface> # Poll this site first each cycle. poll pop.provider.net proto pop3 user "jsmith" with pass "secret1" is "smith" here user jones with pass "secret2" is "jjones" here with options keep # Poll this site second, unless Lord Voldemort zaps us first. poll billywig.hogwarts.com with proto imap: user harry_potter with pass "floo" is harry_potter here # Poll this site third in the cycle. # Password will be fetched from ~/.netrc poll mailhost.net with proto imap: user esr is esr here Glade Troff XSLT fetchmail Regex "x.z?z{1,3}y" SQL SELECT * FROM TABLE WHERE NAME LIKE '%SMI' ORDER BY NAME DSLs 2010 - 7
- 8. Origins • It hasalways been a holy grail of computer users to be able to speak directly to our computers • Different languages have pushed the boundaries further than others – APT for numerically controlled machine tools (1957) – BNF (1959), COBOL, 4GLs – LISP & Smalltalk – Unix "little languages" DSLs 2010 - 8 ©ASERT2006-2010
- 9. Origins • It hasalways been a holy grail of computer users to be able to speak directly to our computers DSLs 2010 - 9 http://dsal.uchicago.edu/reference/gazetteer/pager.html?objectid=DS405.1.I34_V02_298.gif ©ASERT2006-2010
- 10. Origins: LISP &Smalltalk “In Lisp, you don’t just write your program down toward the language, you also build the language up toward your program” - Paul Graham “When [Smalltalk] is used to describe an application system, the developer extends Smalltalk, creating a domain-specific language by adding a new vocabulary of language elements ...” - Adele Goldberg DSLs 2010 - 10 ©ASERT2006-2010
- 11. Origins: Minilanguages... Source: TheArt of Unix Programming:Taxonomy of languages: http://www.faqs.org/docs/artu/ch08s01.html %!PS-Adobe-3.0 %%Creator: groff version 1.20.1 ... 597.6 12 72 12 DL(increasing loopiness)297.71 8.2 Q(/etc/passwd)102.67 94.6 Q(.ne)110.715 106.6 Q(wsrc)-.25 E(SNG)195.2 100.6 Q(re)243.8 94.6 Q (ge)-.15 E(xps)-.15 E(Glade)247.26 106.6 Q(m4)306.81 58.6 Q -1(Ya)303.43 70.6 S(cc)1 E(Le)305.5 82.6 Q(x)-.15 E(mak)302.42 94.6 Q(e)-.1 E(XSL) 301.16 106.6 Q(T)-.92 E(pic)307.09 118.6 Q(tbl)307.92 130.6 Q(eqn)305.98 142.6 Q(fetchmail)344.715 82.6 Q -.15(aw)355.345 94.6 S(k).15 E(trof) 354.84 106.6 Q(f)-.25 E(Postscript)343.875 118.6 Q(dc)412.88 94.6 Q(bc) 412.88 106.6 Q(Emacs Lisp)462.53 94.6 Q(Ja)465.395 106.6 Q -.25(va)-.2 G (Script).25 E(sh)529.075 94.6 Q(tcl)528.52 106.6 Q(Perl)565.065 88.6 Q (Python)558.95 100.6 Q(Ja)564.46 112.6 Q -.25(va)-.2 G 0 Cg EP %%Trailer end %%EOF Input DSL: pic for above picture Output "DSL": Postscript for above picture # Minilanguage taxonomy # Base ellipses define smallellipse {ellipse width 3.0 height 1.5} M: ellipse width 3.0 height 1.8 fill 0.2 line from M.n to M.s dashed D: smallellipse() with .e at M.w + (0.8, 0) line from D.n to D.s dashed I: smallellipse() with .w at M.e - (0.8, 0) # Arrow headings arrow from D.w + (0.4, 0.8) to D.e + (-0.4, 0.8) "flat to structured" "" at last arrow.c ... # Interpreters "Emacs Lisp" "JavaScript" at 0.25 between M.e and I.e "sh" "tcl" at 0.55 between M.e and I.e "Perl" "Python" "Java" at 0.8 between M.e and I.e DSLs 2010 - 11
- 12. ...Origins: Minilanguages PowerPoint DSLfor previous slide import builder.PowerPointBuilder def name = 'minilanguages' assert new File("${name}.pic').exists() "groff -e -p ${name}.pic > ${name}.ps".execute() "gs -q -sDEVICE='ppmraw' -g2600x3500 -r300x300 -sOutputFile='-' -dBATCH ↵ –dNOPAUSE ${name}.ps | pnmcrop | ppmtogif > ${name}.gif".execute() def builder = new PowerPointBuilder() // Adapted from Erik Pragt builder.slideshow(filename: 'DSLsInGroovy_MiniLanguages.ppt') { slide(title: 'Origins: Minilanguages...') { image( origin: [0, 15], src: "${name}.gif", caption: 'Source: The Art of Unix Programming:Taxonomy...' ) textbox( origin: [5, 100], text: new File("${name}.pic").text, caption: 'Input DSL: pic for above picture' ) textbox( origin: [115, 100], text: new File("${name}.ps").text, caption: 'Output "DSL": Postscript for above picture' ) } } DSLs 2010 - 12
- 13. Subject Matter Experts, BusinessAnalysts...
- 14. HAI CAN HASSTDIO? I HAS A VAR IM IN YR LOOP UP VAR!!1 VISIBLE VAR IZ VAR BIGGER THAN 10? KTHXBYE IM OUTTA YR LOOP KTHXBYE Developer producing LOLCODE
- 15. And in theend... nobody understands each other
- 16. DSL: a potentialsolution? 1616 • Use a more expressive language than a general purpose one • Share a common metaphor of understanding between developers and subject matter experts • Have domain experts help with the design of the business logic of an application • Avoid cluttering business code with too much boilerplate technical code • Cleanly separate business logic from application code • Let business rules have their own lifecycle
- 17. 17 Copyright 2010 SpringSource.Copying, publishing or distributing without express written permission is prohibited. Towards more readibility (1) 20% 17
- 18. 18 Copyright 2010 SpringSource.Copying, publishing or distributing without express written permission is prohibited. Towards more readibility (2) 80%
- 19. Why a DSL? •Advantages: – Domain experts can understand, validate, modify, and often even develop DSL programs – Somewhat self-documenting – Enhance quality, productivity, reliability, maintainability, portability and reusability – Safety; as long as the language constructs are safe any sentence written with them can be considered safe • Disadvantages: – Learning cost vs. limited applicability – Cost of designing, implementing & maintaining DSL as well as the tools/IDEs – Attaining proper scope – Trade-offs between domain- specificity and general- purpose programming language constructs – Efficiency costs – Proliferation of similar non- standard DSLs, i.e. different but similar DSLs used within two insurance companies Source: http://en.wikipedia.org/wiki/Domain-specific_language DSLs 2010 - 19 ©ASERT2006-2010
- 20. DSL usage patterns... •Internal (uses a general purpose language) – AKA embedded – Can be a subset or superset – Can be generated/converted from other "language" – Numerous mechanisms to make as close to the domain as possible • External (custom language) – May involve writing your own traditional parser – Using parser combinators – Interpreting – String grepping • Other characteristics – Functional vs OO DSLs 2010 - 20 ©ASERT2006-2010
- 21. ...DSL usage patterns... Source:DSLs in Action, Debasish Ghosh, Manning now in MEAP DSLs 2010 - 21 ©ASERT2006-2010
- 22. ...DSL usage patterns Source:DSLs in Action, Debasish Ghosh, Manning now in MEAP DSLs 2010 - 22 ©ASERT2006-2010
- 23. DSL usage patterns(Advanced) Source: http://www.spinellis.gr/pubs/jrnl/2000-JSS-DSLPatterns/html/dslpat.html See: Diomidis Spinellis. Notable design patterns for domain specific languages. Journal of Systems and Software, 56(1):91–99, February 2001. ©ASERT2006-2010
- 24. DSLs 2010 -24 ©ASERT2006-2010 What is Groovy? • “Groovy is like a super version of Java. It can leverage Java's enterprise capabilities but also has cool productivity features like closures, DSL support, builders and dynamic typing.” Groovy = Java – boiler plate code + optional dynamic typing + closures + domain specific languages + builders + metaprogramming
- 25. DSLs 2010 -25 ©ASERT2006-2010 Groovy Goodies Overview • Fully object oriented • Closures: reusable and assignable pieces of code • Operators can be overloaded • Multimethods • Literal declaration for lists (arrays), maps, ranges and regular expressions • GPath: efficient object navigation • GroovyBeans • grep and switch • Templates, builder, swing, Ant, markup, XML, SQL, XML-RPC, Scriptom, Grails, tests, Mocks
- 26. Growing Acceptance … Aslow and steady start but now gaining in momentum, maturity and mindshare Now free
- 27. DSLs 2010 -27 ©ASERT2006-2010 The Landscape of JVM Languages Java bytecode calls for static types Dynamic features call for dynamic types optional static types The terms “Java Virtual Machine” and “JVM” mean a Virtual Machine for the Java™ platform.
- 28. DSLs 2010 -28 ©ASERT2006-2010 Groovy Starter System.out.println("Hello, World!"); // supports Java syntax println 'Hello, World!' // but can remove some syntax String name = 'Guillaume' // Explicit typing/awareness println "$name, I'll get the car." // Gstring (interpolation) def longer = """${name}, the car is in the next row.""" // multi-line, implicit type assert 0.5 == 1/2 // BigDecimal equals() assert 0.1 + 0.2 == 0.3 // and arithmetic def printSize(obj) { // implicit/duck typing print obj?.size() // safe dereferencing } def pets = ['ant', 'bee', 'cat'] // native list syntax pets.each { pet -> // closure support assert pet < 'dog' // overloading '<' on String } // or: for (pet in pets)...
- 29. A Better Java... DSLs2010 - 29 ©ASERT2006-2010 import java.util.List; import java.util.ArrayList; class Erase { private List removeLongerThan(List strings, int length) { List result = new ArrayList(); for (int i = 0; i < strings.size(); i++) { String s = (String) strings.get(i); if (s.length() <= length) { result.add(s); } } return result; } public static void main(String[] args) { List names = new ArrayList(); names.add("Ted"); names.add("Fred"); names.add("Jed"); names.add("Ned"); System.out.println(names); Erase e = new Erase(); List shortNames = e.removeLongerThan(names, 3); System.out.println(shortNames.size()); for (int i = 0; i < shortNames.size(); i++) { String s = (String) shortNames.get(i); System.out.println(s); } } } This code is valid Java and valid Groovy Based on an example by Jim Weirich & Ted Leung
- 30. ...A Better Java... DSLs2010 - 30 ©ASERT2006-2010 import java.util.List; import java.util.ArrayList; class Erase { private List removeLongerThan(List strings, int length) { List result = new ArrayList(); for (int i = 0; i < strings.size(); i++) { String s = (String) strings.get(i); if (s.length() <= length) { result.add(s); } } return result; } public static void main(String[] args) { List names = new ArrayList(); names.add("Ted"); names.add("Fred"); names.add("Jed"); names.add("Ned"); System.out.println(names); Erase e = new Erase(); List shortNames = e.removeLongerThan(names, 3); System.out.println(shortNames.size()); for (int i = 0; i < shortNames.size(); i++) { String s = (String) shortNames.get(i); System.out.println(s); } } } Do the semicolons add anything? And shouldn‟t we us more modern list notation? Why not import common libraries?
- 31. ...A Better Java... DSLs2010 - 31 ©ASERT2006-2010 class Erase { private List removeLongerThan(List strings, int length) { List result = new ArrayList() for (String s in strings) { if (s.length() <= length) { result.add(s) } } return result } public static void main(String[] args) { List names = new ArrayList() names.add("Ted"); names.add("Fred") names.add("Jed"); names.add("Ned") System.out.println(names) Erase e = new Erase() List shortNames = e.removeLongerThan(names, 3) System.out.println(shortNames.size()) for (String s in shortNames) { System.out.println(s) } } }
- 32. ...A Better Java... DSLs2010 - 32 ©ASERT2006-2010 class Erase { private List removeLongerThan(List strings, int length) { List result = new ArrayList() for (String s in strings) { if (s.length() <= length) { result.add(s) } } return result } public static void main(String[] args) { List names = new ArrayList() names.add("Ted"); names.add("Fred") names.add("Jed"); names.add("Ned") System.out.println(names) Erase e = new Erase() List shortNames = e.removeLongerThan(names, 3) System.out.println(shortNames.size()) for (String s in shortNames) { System.out.println(s) } } } Do we need the static types? Must we always have a main method and class definition? How about improved consistency?
- 33. ...A Better Java... DSLs2010 - 33 ©ASERT2006-2010 def removeLongerThan(strings, length) { def result = new ArrayList() for (s in strings) { if (s.size() <= length) { result.add(s) } } return result } names = new ArrayList() names.add("Ted") names.add("Fred") names.add("Jed") names.add("Ned") System.out.println(names) shortNames = removeLongerThan(names, 3) System.out.println(shortNames.size()) for (s in shortNames) { System.out.println(s) }
- 34. ...A Better Java... DSLs2010 - 34 ©ASERT2006-2010 def removeLongerThan(strings, length) { def result = new ArrayList() for (s in strings) { if (s.size() <= length) { result.add(s) } } return result } names = new ArrayList() names.add("Ted") names.add("Fred") names.add("Jed") names.add("Ned") System.out.println(names) shortNames = removeLongerThan(names, 3) System.out.println(shortNames.size()) for (s in shortNames) { System.out.println(s) } Shouldn‟t we have special notation for lists? And special facilities for list processing? Is „return‟ needed at end?
- 35. ...A Better Java... DSLs2010 - 35 ©ASERT2006-2010 def removeLongerThan(strings, length) { strings.findAll{ it.size() <= length } } names = ["Ted", "Fred", "Jed", "Ned"] System.out.println(names) shortNames = removeLongerThan(names, 3) System.out.println(shortNames.size()) shortNames.each{ System.out.println(s) }
- 36. ...A Better Java... DSLs2010 - 36 ©ASERT2006-2010 def removeLongerThan(strings, length) { strings.findAll{ it.size() <= length } } names = ["Ted", "Fred", "Jed", "Ned"] System.out.println(names) shortNames = removeLongerThan(names, 3) System.out.println(shortNames.size()) shortNames.each{ System.out.println(s) } Is the method now needed? Easier ways to use common methods? Are brackets required here?
- 37. ...A Better Java... DSLs2010 - 37 ©ASERT2006-2010 names = ["Ted", "Fred", "Jed", "Ned"] println names shortNames = names.findAll{ it.size() <= 3 } println shortNames.size() shortNames.each{ println it }
- 38. ...A Better Java DSLs2010 - 38 ©ASERT2006-2010 names = ["Ted", "Fred", "Jed", "Ned"] println names shortNames = names.findAll{ it.size() <= 3 } println shortNames.size() shortNames.each{ println it } ["Ted", "Fred", "Jed", "Ned"] 3 Ted Jed Ned
- 39. Grapes / Grab DSLs2010 - 39 ©ASERT2006-2010 // Google Collections example @Grab('com.google.collections:google-collections:1.0') import com.google.common.collect.HashBiMap HashBiMap fruit = [grape:'purple', lemon:'yellow', lime:'green'] assert fruit.lemon == 'yellow' assert fruit.inverse().yellow == 'lemon'
- 40. Malleable Syntax DSLs 2010- 40 ©ASERT2006-2010 order to buy 200.shares of GOOG { limitPrice 500 allOrNone false at the value of { qty * unitPrice - 100 } } take 2.pills of chloroquinine after 6.hours Groovy 1.8+ def "length of Spock's & his friends' names"() { expect: name.size() == length where: name | length "Spock" | 5 "Kirk" | 4 "Scotty" | 6 }
- 41. 41 Copyright 2010 SpringSource.Copying, publishing or distributing without express written permission is prohibited. Real-life Groovy DSL examples • Anti-malaria drug resistance simulation • Human Resources employee skills representation • Insurance policies risk calculation engine • Loan acceptance rules engine for a financial platform • Mathematica-like lingua for nuclear safety simulations • Market data feeds evolution scenarios • and more...
- 42. 42 Copyright 2010 SpringSource.Copying, publishing or distributing without express written permission is prohibited. DSLs within the Groovy Ecosystem • Testing DSLs – EasyB, Spock, JBehave, … • Builders – MarkupBuilder, SwingBuilder • Build Tool DSLs – AntBuilder, Gant, Gradle • Grails – BeanBuilder, Criteria, ConfigSlurper • GPars – DSL for concurrent activities • and more...
- 43.
- 44. ...Testing DSLs: Spock... ©ASERT2006-2010 •Testing framework for Java and Groovy • Highly expressive specification language – No assertion API – No record & replay mocking API – No superfluous annotations – Meaningful assert error messages – Extensible – Compatible with JUnit reportingwise @Speck @RunWith(Sputnik) class PublisherSubscriberSpeck { def "events are received by all subscribers"() { def pub = new Publisher() def sub1 = Mock(Subscriber) def sub2 = Mock(Subscriber) pub.subscribers << sub1 << sub2 when: pub.send("event") then: 1 * sub1.receive("event") 1 * sub2.receive("event") } } DSLs 2010 - 44
- 45. ...Testing DSLs: Spock... ©ASERT2006-2010 importcom.gargoylesoftware.htmlunit.WebClient import spock.lang.* import org.junit.runner.RunWith @Speck () @RunWith (Sputnik) class TestSimpBlogSpock { def page, subheadings, para, form, result @Unroll("When #author posts a #category blog with content '#content' it sho def "when creating a new blog entry"() { given: page = new WebClient().getPage('http://localhost:8080/postForm') form = page.getFormByName('post') when: form.getInputByName('title').setValueAttribute("$author was here (and s form.getSelectByName('category').getOptions().find { it.text == categor form.getSelectByName('author').getOptions().find { it.text == author }. form.getTextAreaByName('content').setText(content) result = form.getInputByName('btnPost').click() subheadings = result.getElementsByTagName('h3') para = result.getByXPath('//TABLE//TR/TD/P')[0] ... DSLs 2010 - 45
- 46. ... Testing DSLs:Spock ©ASERT2006-2010 ... then: page.titleText == 'Welcome to SimpBlog' result.getElementsByTagName('h1').item(0).textContent.matches("Post.*: $au subheadings.item(1).textContent == "Category: $category" subheadings.item(2).textContent == "Author: $author" and: para.textContent == content where: author << ['Bart', 'Homer', 'Lisa'] category << ['Home', 'Work', 'Food'] content << ['foo', 'bar', 'baz'] } } // Optional use of 'and:' DSLs 2010 - 46
- 47. ©ASERT2006-2010 Testing DSLs: EasyB… •Description: BDD, Rspec-like testing library narrative 'segment flown', { as_a 'frequent flyer' i_want 'to accrue rewards points for every segment I fly' so_that 'I can receive free flights for my dedication to the airline' } scenario 'segment flown', { given 'a frequent flyer with a rewards balance of 1500 points' when 'that flyer completes a segment worth 500 points' then 'that flyer has a new rewards balance of 2000 points' } scenario 'segment flown', { given 'a frequent flyer with a rewards balance of 1500 points', { flyer = new FrequentFlyer(1500) } when 'that flyer completes a segment worth 500 points', { flyer.fly(new Segment(500)) } then 'that flyer has a new rewards balance of 2000 points', { flyer.pointsBalance.shouldBe 2000 } } DSLs 2010 - 47
- 48. …Testing DSLs: EasyB •When run will be marked as pending – perfect for ATDD ©ASERT2006-2010 scenario "Bart posts a new blog entry", { given "we are on the create blog entry page" when "I have entered 'Bart was here' as the title" and "I have entered 'Cowabunga Dude!' into the content" and "I have selected 'Home' as the category" and "I have selected 'Bart' as the author" and "I click the 'Create Post' button" then "I expect the entry to be posted" } DSLs 2010 - 48
- 49. Testing DSLS: Cucumber... ©ASERT2006-2010 #language: en @newpost Feature: New Blog Post In order to create a new blog entry Bloggers should be able to select their name and category and enter text Scenario: New Posting Given we are on the create blog entry page When I have entered "Bart was here" as the title And I have entered "Cowabunga Dude!" as the content And I have selected "Home" from the "category" dropdown And I have selected "Bart" from the "author" dropdown And I click the 'Create Post' button Then I should see a heading message matching "Post.*: Bart was here.*" DSLs 2010 - 49
- 50. ... Testing DSLS:Cucumber... ©ASERT2006-2010 DSLs 2010 - 50
- 51. ...Testing DSLS: Cucumber ©ASERT2006-2010 importcom.gargoylesoftware.htmlunit.WebClient this.metaClass.mixin(cuke4duke.GroovyDsl) Given ~/we are on the create blog entry page/, { -> page = new WebClient().getPage('http://localhost:8080/postForm') } When(~/I have entered "(.*)" as the title/) {String title -> form = page.getFormByName('post') form.getInputByName('title').setValueAttribute(title + ' (and so was Cucumber)') } When(~'I have entered "(.*)" as the content') {String content -> form.getTextAreaByName('content').setText(content) } When(~'I have selected "(.*)" from the "(.*)" dropdown') {String option, String name -> form.getSelectByName(name).getOptions().find { it.text == option }.setSelected(true) } When(~"I click the 'Create Post' button") { -> result = form.getInputByName('btnPost').click() } Then(~'I should see a heading message matching "(.*)"') {String pattern -> // ensureThat result.getElementsByTagName('h1').item(0).textContent.matches(pattern) assert result.getElementsByTagName('h1').item(0).textContent.matches(pattern) } DSLs 2010 - 51
- 52. Grails Criteria DSLs 2010- 52 ©ASERT2006-2010 // Account is a POJO in our domain/model def c = Account.createCriteria() def results = c { like("holderFirstName", "Fred%") and { between("balance", 500, 1000) eq("branch", "London") } maxResults(10) order("holderLastName", "desc") } // source: Grails doco: 5. Object Relational Mapping (GORM): 5.4.2 Criteria
- 53. Grails Criteria Example DSLs2010 - 53 ©ASERT2006-2010 // Book is a POJO in our domain/model def book = Book.findByTitle("The Stand") book = Book.findByTitleLike("Harry Pot%") book = Book.findByReleaseDateBetween( firstDate, secondDate ) book = Book.findByReleaseDateGreaterThan( someDate ) book = Book.findByTitleLikeOrReleaseDateLessThan( "%Something%", someDate ) books = Book.findAllByTitleLikeAndReleaseDateGreaterThan( "%Java%", new Date()-30) // source: Grails doco: 5. Object Relational Mapping (GORM): 5.4.1 Dynamic Finders
- 54. Grails Bean BuilderExample DSLs 2010 - 54 ©ASERT2006-2010 bb.beans { marge(Person) { name = "marge" husband = { Person p -> name = "homer" age = 45 props = [overweight:true, height:"1.8m"] } children = [bart, lisa] } bart(Person) { name = "Bart" age = 11 } lisa(Person) { name = "Lisa" age = 9 } } // source: 14. Grails and Spring: 14.3 Runtime Spring with the Beans DSL
- 55. GPars... import static org.gparallelizer.actors.pooledActors.PooledActors.* //create a new actor that prints out received messages def console = actor { loop { react {message -> println message } } } // start the actor and send it a message console.start() console.send('Message') DSLs 2010 - 55
- 56. ...GPars import static org.gparallelizer.dataflow.DataFlow.thread finaldef x = new DataFlowVariable() final def y = new DataFlowVariable() final def z = new DataFlowVariable() thread { z << ~x + ~y println "Result: ${~z}" } thread { x << 10 } thread { y << 5 } No race-conditions No deadlocks No live-locks Completely deterministic programs BEAUTIFUL code DSLs 2010 - 56
- 57. Topics • Introduction Groovy DSLFeatures • A Week In The Life Of DSL INC • Summary • More Info DSLs 2010 - 57 ©ASERT2006-2010
- 58. Groovy DSL Features DSLs2010 - 58 ©ASERT2006-2010
- 59. Import / ImportStatic • Imports • Static Imports DSLs 2010 - 59 ©ASERT2006-2010 @Grab('com.google.collections:google-collections:1.0') import com.google.common.collect.HashBiMap as HashMap def m = new HashMap() m.key = 'value' assert m.inverse().value == 'key' import static java.util.Calendar.getInstance as now println now().format('yyyy/MMM/dd') What Java gives us plus aliases
- 60. Static Imports... DSLs 2010- 60 ©ASERT2006-2010 import groovy.swing.SwingXBuilder import static java.awt.Color.* import static java.lang.Math.* def swing = new SwingXBuilder() def frame = swing.frame(size: [300, 300]) { graph(plots: [ [GREEN, {value -> sin(value)}], [BLUE, {value -> cos(value)}], [RED, {value -> tan(value)}] ]) }.show() Java Static Imports Discussed later: Builders Closures
- 61. ...Static Imports... DSLs 2010- 61 ©ASERT2006-2010 import groovy.swing.SwingXBuilder import static java.awt.Color.* import static java.lang.Math.* def swing = new SwingXBuilder() def frame = swing.frame(size: [300, 300]) { graph(plots: [ [GREEN, {value -> sin(value)}], [BLUE, {value -> cos(value)}], [RED, {value -> tan(value)}] ]) }.show() Java gives us this
- 62. ...Static Imports... DSLs 2010- 62 ©ASERT2006-2010 import groovy.swing.SwingXBuilder import static java.awt.Color.* import static java.lang.Math.* def swing = new SwingXBuilder() def frame = swing.frame(size: [300, 300]) { graph(plots: [ [GREEN, {value -> sin(value)}], [BLUE, {value -> cos(value)}], [RED, {value -> tan(value)}] ]) }.show() Java gives us this
- 63. ...Static Imports... DSLs 2010- 63 ©ASERT2006-2010 Source: http://www.thedoghousediaries.com/?p=1406
- 64. ...Static Imports DSLs 2010- 64 ©ASERT2006-2010 import groovy.swing.SwingXBuilder import static java.lang.Math.* import static java.awt.Color.GREEN as Lime import static java.awt.Color.BLUE as Sky import static java.awt.Color.RED as Maraschino def swing = new SwingXBuilder() def frame = swing.frame(size: [300, 300]) { graph(plots: [ [Lime, {value -> sin(value)}], [Sky, {value -> cos(value)}], [Maraschino, {value -> tan(value)}] ]) }.show() Java doesn‟t give us this!
- 65. Literal Syntax Conventions •Lists – Special syntax for list literals – Additional common methods (operator overloading) • Maps – Special syntax for map literals – Additional common methods • Ranges – Special syntax for various kinds of ranges DSLs 2010 - 65 ©ASERT2006-2010 def list = [3, new Date(), 'Jan'] assert list + list == list * 2 def map = [a: 1, b: 2] assert map['a'] == 1 && map.b == 2 def letters = 'a'..'z' def numbers = 0..<10
- 66. Literal Syntax Conventionsin DSLs DSLs 2010 - 66 ©ASERT2006-2010 import static java.util.Calendar.getInstance as getNow import static java.util.Calendar.* def discount = [normal:0, silver:5, gold:10] def roomrate = [weekday:150, weekend:95] for (level in ['normal', 'silver', 'gold']) { def multiplier = 1 - discount[level] / 100 print 'Your room rate is: ' if (now[DAY_OF_WEEK] in MONDAY..FRIDAY) println roomrate.weekday * multiplier else println roomrate.weekend * multiplier } Your room rate is: 150 Your room rate is: 142.50 Your room rate is: 135.0 Literal list & map syntax Ranges Also Static import aliases BigDecimal arithmetic
- 67. Compact Syntax... • Java •Groovy DSLs 2010 - 67 ©ASERT2006-2010 public class BuySharesJava { public static void buyShares(int qty, String name) { // business logic here ... System.out.println("buying " + qty + " shares of " + name); } public static void main(String[] args) { buyShares(3, "BHP"); } } def buyShares(qty, name) { // business logic here ... println "buying $qty shares of $name" } buyShares 3, 'BHP' Script syntax Conventions for visibility GDK methods: println Implicit typing GString interpolation Optional brackets & „;‟
- 68. ...Compact Syntax... • Java •Groovy DSLs 2010 - 68 ©ASERT2006-2010 import java.util.Date; import java.util.HashMap; import java.util.Map; public class ProcessCustomerJava { public static void printDetails(Map<String, String> cust) { System.out.println("Details as at: " + new Date()); String first = cust.get("first"); System.out.println("First name: " + first); String last = cust.get("last"); System.out.println("Last name: " + (last != null ? last : "unknown")); } public static void main(String[] args) { Map<String, String> details = new HashMap<String, String>(); details.put("first", "John"); details.put("last", "Smith"); printDetails(details); } } def printDetails(cust) { println """Details as at: ${new Date()} First name: $cust.first Last name: ${cust.last ?: 'unknown'}""" } printDetails first: 'John', last: 'Smith' Script syntax, Named params, Extra imports Conventions for visibility, GDK methods Implicit typing, Multi-line GString Elvis operator, Optional brackets & „;‟
- 69. ...Compact Syntax • Java •Groovy DSLs 2010 - 69 ©ASERT2006-2010 import java.util.Date; public class ProcessStrongCustomerJava { public static void printDetails(CustomerJ cust) { System.out.println("Details as at: " + new Date()); String first = cust.getFirst(); System.out.println("First name: " + first); String last = cust.getLast(); System.out.println("Last name: " + (last != null ? last : "unknown")); } public static void main(String[] args) { CustomerJ c = new CustomerJ(); c.setFirst("John"); c.setLast("Smith"); printDetails(c); } } class CustomerJ { private String first; private String last; public String getFirst() { return first; } public void setFirst(String first) { this.first = first; } public String getLast() { return last; } public void setLast(String last) { this.last = last; } } class CustomerG { String first, last } def printDetails(cust) { println """Details as at: ${new Date()} First name: $cust.first Last name: ${cust.last ?: 'unknown'}""" } printDetails new CustomerG(first: 'John', last: 'Smith') Plus: Named params for constructors JavaBean conventions Leverage Duck Typing
- 70. Using With Example DSLs2010 - 70 ©ASERT2006-2010 letters = ['a', 'b', 'c'] range = 'b'..'d' letters.with { add 'd' remove 'a' } assert letters == range map = [a:10, b:4, c:7] map.with { assert (a + b) / c == 2 } Just normal methods for ArrayList here
- 71. Closures... • Traditional mainstreamlanguages – Data can be stored in variables, passed around, combined in structured ways to form more complex data; code stays put where it is defined • Languages supporting closures – Data and code can be stored in variables, passed around, combined in structured ways to form more complex algorithms and data; functional coding style DSLs 2010 - 71 ©ASERT2006-2010 doubleNum = { num -> num * 2 } println doubleNum(3) // => 6 processThenPrint = { num, closure -> num = closure(num); println "num is $num" } processThenPrint(3, doubleNum) // => num is 6 processThenPrint(10) { it / 2 } // => num is 5
- 72. ...Closures... DSLs 2010 -72 ©ASERT2006-2010 int myConst = 4 def multiplier = { number -> number * myConst } assert multiplier(10) == 40 Closure other = { it + myConst } assert other.call(10) == 14 def twice = { it * 2 } // anonymous functions assert twice(10) == 20 // implemented as Closures Name
- 73. ...Closures... DSLs 2010 -73 ©ASERT2006-2010 int myConst = 4 def multiplier = { number -> number * myConst } assert multiplier(10) == 40 Closure other = { it + myConst } assert other.call(10) == 14 def twice = { it * 2 } // anonymous functions assert twice(10) == 20 // implemented as Closures Code
- 74. ...Closures... DSLs 2010 -74 ©ASERT2006-2010 int myConst = 4 def multiplier = { number -> number * myConst } assert multiplier(10) == 40 Closure other = { it + myConst } assert other.call(10) == 14 def twice = { it * 2 } // anonymous functions assert twice(10) == 20 // implemented as Closures Parameter(s) Default parameter
- 75. ...Closures... DSLs 2010 -75 ©ASERT2006-2010 int myConst = 4 def multiplier = { number -> number * myConst } assert multiplier(10) == 40 Closure other = { it + myConst } assert other.call(10) == 14 def twice = { it * 2 } // anonymous functions assert twice(10) == 20 // implemented as Closures Call closure Alternative syntax
- 76. ...Closures... DSLs 2010 -76 ©ASERT2006-2010 int myConst = 4 def multiplier = { number -> number * myConst } assert multiplier(10) == 40 Closure other = { it + myConst } assert other.call(10) == 14 def twice = { it * 2 } // anonymous functions assert twice(10) == 20 // implemented as Closures Free variable
- 77. ...Closures... DSLs 2010 -77 ©ASERT2006-2010 int myConst = 4 def multiplier = { number -> number * myConst } assert multiplier(10) == 40 Closure other = { it + myConst } assert other.call(10) == 14 def twice = { it * 2 } // anonymous functions assert twice(10) == 20 // implemented as Closures Bound to environment/context when called
- 78. Closures in DSLs... DSLs2010 - 78 ©ASERT2006-2010 import static java.util.Calendar.* def cart1 = [ [qty: 3, unitPrice: 50.0, gift: true, name: 'Groovy in Action Book'], [qty: 1, unitPrice: 40.0, gift: false, name: 'Grails in Action eBook'], [qty: 2, unitPrice: 25.0, gift: true, name: 'Avatar DVD'] ] def cart2 = [ [qty: 1, unitPrice: 50.0, gift: true, name: 'Groovy in Action Book'], [qty: 2, unitPrice: 30.0, gift: false, name: 'Avatar 3D DVD'] ] // ... Nothing special here. Just a list of maps.
- 79. ... Closures inDSLs... DSLs 2010 - 79 ©ASERT2006-2010 // ... def noDiscount = { it.unitPrice * it.qty } def tenPercentOffAll = { it.unitPrice * it.qty * 0.9 } def tenPercentOffGifts = { it.with { unitPrice * qty * (gift ? 0.9 : 1.0) } } def tenPercentOffOverForty = { it.with { unitPrice * qty * (unitPrice > 40 ? 0.9 : 1.0) } } def tenPercentOffBooks = { it.with { unitPrice * qty * (name.contains('Book') ? 0.9 : 1.0) } } def tenPercentOffDVDs = { it.with { unitPrice * qty * (name.contains('DVD') ? 0.9 : 1.0) } } def buyThreeGetOneFree = { it.with { unitPrice * (qty % 3 + 2 * qty.intdiv(3)) } } // ... Closure Name
- 80. ... Closures inDSLs... DSLs 2010 - 80 ©ASERT2006-2010 // ... def noDiscount = { it.unitPrice * it.qty } def tenPercentOffAll = { it.unitPrice * it.qty * 0.9 } def tenPercentOffGifts = { it.with { unitPrice * qty * (gift ? 0.9 : 1.0) } } def tenPercentOffOverForty = { it.with { unitPrice * qty * (unitPrice > 40 ? 0.9 : 1.0) } } def tenPercentOffBooks = { it.with { unitPrice * qty * (name.contains('Book') ? 0.9 : 1.0) } } def tenPercentOffDVDs = { it.with { unitPrice * qty * (name.contains('DVD') ? 0.9 : 1.0) } } def buyThreeGetOneFree = { it.with { unitPrice * (qty % 3 + 2 * qty.intdiv(3)) } } // ... Closure Code
- 81. ... Closures inDSLs DSLs 2010 - 81 ©ASERT2006-2010 // ... def specials = [noDiscount, tenPercentOffAll, tenPercentOffGifts, tenPercentOffOverForty, tenPercentOffBooks, tenPercentOffDVDs, buyThreeGetOneFree] [ SUNDAY..SATURDAY, [cart1, cart2] ].combinations().each { day, cart -> printf "%d %2.2fn", day, cart.sum(specials[day-1]) } 1 240.00 2 216.00 3 220.00 4 225.00 5 221.00 6 235.00 7 190.00 1 110.00 2 99.00 3 105.00 4 105.00 5 105.00 6 104.00 7 110.00
- 82. Operator Overloading Example DSLs2010 - 82 ©ASERT2006-2010 BigDecimal a = new BigDecimal(3.5d); BigDecimal b = new BigDecimal(4.0d); assert a.multiply(b).compareTo(new BigDecimal(14.0d)) == 0; assert a.multiply(b).equals(new BigDecimal(14.0d).setScale(1)); def c = 3.5, d = 4.0 assert c * d == 14.0 • Java • Groovy
- 83. Groovy Lab Example DSLs2010 - 83 ©ASERT2006-2010 // require GroovyLab import static org.math.array.Matrix.* import static org.math.plot.Plot.* def A = rand(10,3) // random Matrix of 10 rows and 3 columns def B = fill(10,3,1.0) // one Matrix of 10 rows and 3 columns def C = A + B // support for matrix addition with "+" or "-" def D = A - 2.0 // support for number addition with "+" or "-" def E = A * B // support for matrix multiplication or division def F = rand(3,3) def G = F**(-1) // support for matrix power (with integers only) println A // display Matrix content plot("A",A,"SCATTER") // plot Matrix values as ScatterPlot def M = rand(5,5) + id(5) // Eigenvalues decomposition println "M=n" + M println "V=n" + V(M) println "D=n" + D(M) println "M~n" + (V(M) * D(M) * V(M)**(-1))
- 84. ©ASERT2006-2010 Better Control Structures:Switch Poker… suits = 'SHDC' ranks = '23456789TJQKA' suit = { String card -> suits.indexOf(card[1]) } rank = { String card -> ranks.indexOf(card[0]) } rankSizes = { List cards -> cards.groupBy(rank).collect{ k, v -> v.size() }.sort() } rankValues = { List cards -> cards.collect{ rank(it) }.sort() } // ... 8C TS KC 9H 4S 7D 2S 5D 3S AC hand1 hand2 println rankSizes(["7S", "7H", "2H", "7D", "AH"]) // => [1, 1, 3] DSLs 2010 - 84
- 85. ©ASERT2006-2010 …Better Control Structures:Switch Poker… // ... flush = { List cards -> cards.groupBy(suit).size() == 1 } straight = { def v = rankValues(it); v == v[0]..v[0]+4 } straightFlush = { List cards -> straight(cards) && flush(cards) } fourOfAKind = { List cards -> rankSizes(cards) == [1, 4] } fullHouse = { List cards -> rankSizes(cards) == [2, 3] } threeOfAKind = { List cards -> rankSizes(cards) == [1, 1, 3] } twoPair = { List cards -> rankSizes(cards) == [1, 2, 2] } pair = { List cards -> rankSizes(cards) == [1, 1, 1, 2] } // ... DSLs 2010 - 85
- 86. ©ASERT2006-2010 … Better ControlStructures: Switch Poker // ... def rankHand(List cards) { switch (cards) { case straightFlush : return 9 case fourOfAKind : return 8 case fullHouse : return 7 case flush : return 6 case straight : return 5 case threeOfAKind : return 4 case twoPair : return 3 case pair : return 2 default : return 1 } } // ... DSLs 2010 - 86
- 87. Type Transformation Example DSLs2010 - 87 ©ASERT2006-2010 class InventoryItem { def weight, name InventoryItem(Map m) { this.weight = m.weight; this.name = m.name } InventoryItem(weight, name) { this.weight = weight; this.name = name } InventoryItem(String s) { s.find(/weight=(d*)/) { all, w -> this.weight = w } s.find(/name=(.*)/) { all, n -> this.name = n } } } def room = [:] def gold = [weight:50, name:'Gold'] as InventoryItem def emerald = [10, 'Emerald'] as InventoryItem def dagger = ['weight=5, name=Dagger'] as InventoryItem room.contents = [gold, emerald, dagger] room.contents.each{ println it.dump() }
- 88. DSLs 2010 -88 Groovy DSL Features ©ASERT2006-2010
- 89. Metaprogramming • Runtime Metaprogramming –Categories including DGM – invokeMethod, methodMissing, getProperty – GroovyInterceptable – ExpandoMetaClass DSLs 2010 - 89 ©ASERT2006-2010
- 90. DSLs 2010 -90 ©ASERT2006-2010 Builders… <html> <head> <title>Hello</title> </head> <body> <ul> <li>world 1</li> <li>world 2</li> <li>world 3</li> <li>world 4</li> <li>world 5</li> </ul> </body> </html> import groovy.xml.* def page = new MarkupBuilder() page.html { head { title 'Hello' } body { ul { for (count in 1..5) { li "world $count" } } } } • MarkupBuilder
- 91. ...Builders… DSLs 2010 -91 ©ASERT2006-2010 def colors = ['red','darkOrange','blue','darkGreen'] (0..3).each { index -> star( cx: 50 + (index*110), cy: 50, or: 40, ir: 15, borderColor: 'black', count: 2+index, fill: colors[index] ) star( cx: 50 + (index*110), cy: 140, or: 40, ir: 15, borderColor: 'black‘, count: 7+index, fill: colors[index] ) } • GraphicsBuilder
- 92. …Builders new AntBuilder().with { echo(file:'Temp.java',''' class Temp { public static void main(String[] args) { System.out.println("Hello"); } } ''') javac(srcdir:'.', includes:'Temp.java', fork:'true') java(classpath:'.', classname:'Temp', fork:'true') echo('Done') } // => // [javac] Compiling 1 source file // [java] Hello // [echo] Done ©ASERT2006-2010 DSLs 2010 - 92
- 93. 93 Copyright 2010 SpringSource.Copying, publishing or distributing without express written permission is prohibited. A builder for HR
- 94. DSLs 2010 -94 ©ASERT2006-2010 ExpandoMetaClass… import static java.lang.Character.isUpperCase String.metaClass.swapCase = { delegate.collect { ch -> isUpperCase(ch as char) ? ch.toLowerCase() : ch.toUpperCase() }.join() } println new Date().toString().swapCase() // => sUN nOV 09 17:30:06 est 2008 List.metaClass.sizeDoubled = {-> delegate.size() * 2 } LinkedList list = [] list << 1 list << 2 assert 4 == list.sizeDoubled()
- 95. DSLs 2010 -95 ©ASERT2006-2010 …ExpandoMetaClass class Person { String name } class MortgageLender { def borrowMoney() { "buy house" } } def lender = new MortgageLender() Person.metaClass.buyHouse = lender.&borrowMoney def p = new Person() assert "buy house" == p.buyHouse()
- 96. Adding your owncontrol structures • Thread enhancement DSLs 2010 - 96 ROCK! . 25 . 33 . 34 . 35 . 36 .. 131 .. 134 .. 137 .. 138 .. 139 ... 232 ... 234 ... 237 ... 238 ... 239 .... 334 .... 336 .... 337 .... 338 .... 339 import java.util.concurrent.locks.ReentrantLock import static System.currentTimeMillis as now def startTime = now() ReentrantLock.metaClass.withLock = { critical -> lock() try { critical() } finally { unlock() } } def lock = new ReentrantLock() def worker = { threadNum -> 4.times { count -> lock.withLock { print " " * threadNum print "." * (count + 1) println " ${now() - startTime}" } Thread.sleep 100 } } 5.times { Thread.start worker.curry(it) } println "ROCK!" Source: http://chrisbroadfoot.id.au/articles/2008/08/06/groovy-threads
- 97. EMC DSL… DSLs 2010- 97 ©ASERT2006-2010
- 98. ...EMC Neo4j DSL… DSLs2010 - 98 ©ASERT2006-2010 @GrabResolver(name= 'neo4j-public-repo', root= 'http://m2.neo4j.org') @Grab('org.neo4j:neo4j-kernel:1.1.1') import org.neo4j.kernel.EmbeddedGraphDatabase import org.neo4j.graphdb.* // an enum helper enum MyRelationships implements RelationshipType { knows } // some optional syntactic sugar using EMC DSL Node.metaClass { propertyMissing { String name, val -> delegate.setProperty(name, val) } propertyMissing { String name -> delegate.getProperty(name) } methodMissing { String name, args -> delegate.createRelationshipTo(args[0], MyRelationships."$name") } } Relationship.metaClass { propertyMissing { String name, val -> delegate.setProperty(name, val) } propertyMissing { String name -> delegate.getProperty(name) } } // ...
- 99. …EMC Neo4j DSL DSLs2010 - 99 ©ASERT2006-2010 // ... def graphDb = new EmbeddedGraphDatabase("graphdb") def tx = graphDb.beginTx() def firstNode, secondNode, relationship try { firstNode = graphDb.createNode() secondNode = graphDb.createNode() relationship = firstNode.knows(secondNode) firstNode.message = "Hello," secondNode.message = "world!" relationship.message = "brave Neo4j" tx.success() } finally { tx.finish() println "$firstNode.message $relationship.message $secondNode.message" // => Hello, brave Neo4j world! graphDb.shutdown() }
- 100. Game example... DSLs 2010- 100 ©ASERT2006-2010 // Trying out the game DSL idea by Sten Anderson from: // http://blogs.citytechinc.com/sanderson/?p=92 class GameUtils { static VOWELS = ['a', 'e', 'i', 'o', 'u'] static listItems(things) { def result = '' things.eachWithIndex{ thing, index -> if (index > 0) { if (index == things.size() - 1) result += ' and ' else if (index < things.size() - 1) result += ', ' } result += "${thing.toLowerCase()[0] in VOWELS ? 'an' : 'a'} $thing } result ?: 'nothing' } } import static GameUtils.* ...
- 101. ...Game example... DSLs 2010- 101 ©ASERT2006-2010 ... class Room { def description def contents = [] } ...
- 102. ...Game example... DSLs 2010- 102 ©ASERT2006-2010 ... class Player { def currentRoom def inventory = [] void look() { println "You are in ${currentRoom?.description?:'the void'} which contains ${listItems(currentRoom?.contents)}" } void inv() { println "You are holding ${listItems(inventory)}" } void take(item) { if (currentRoom?.contents?.remove(item)) { inventory << item println "You took the $item" } else { println "I see no $item here" } } ...
- 103. ...Game example... DSLs 2010- 103 ©ASERT2006-2010 ... void drop(item) { if (inventory?.remove(item)) { currentRoom?.contents << item println "You dropped the $item" } else { println "You don't have the $item" } } def propertyMissing(String name) { if (metaClass.respondsTo(this, name)) { this."$name"() } name } } ...
- 104. ...Game example... DSLs 2010- 104 ©ASERT2006-2010 ... Room plainRoom = new Room(description:'a plain white room', contents:['dagger', 'emerald', 'key']) Player player = new Player(currentRoom:plainRoom) player.with { inv look take dagger inv look take emerald inv look take key drop emerald inv look } assert player.inventory == ['dagger', 'key'] ...
- 105. ...Game example DSLs 2010- 105 ©ASERT2006-2010 ... // now try some error conditions plainRoom.description = null player.with { drop gold take gold drop emerald take emerald take emerald look }
- 106. GEP3 example... DSLs 2010- 106 ©ASERT2006-2010 Object.metaClass.please = { clos -> clos(delegate) } Object.metaClass.the = { clos -> delegate[1](clos(delegate[0])) } show = { thing -> [thing, { println it }] } square_root = { Math.sqrt(it) } given = { it } given 100 please show the square_root // ==> 10.0
- 107. ...GEP3 example... DSLs 2010- 107 ©ASERT2006-2010 Object.metaClass.of = { delegate[0](delegate[1](it)) } Object.metaClass.the = { clos -> [delegate[0], clos] } show = [{ println it }] square_root = { Math.sqrt(it) } please = { it } please show the square_root of 100 // ==> 10.0
- 108. ...GEP3 example... DSLs 2010- 108 ©ASERT2006-2010 show = { println it } square_root = { Math.sqrt(it) } def please(action) { [the: { what -> [of: { n -> action(what(n)) }] }] } please show the square_root of 100 // ==> 10.0 Inspiration for this example came from …
- 109. ...GEP3 example... DSLs 2010- 109 ©ASERT2006-2010 // Japanese DSL using GEP3 rules Object.metaClass.を = Object.metaClass.の = { clos -> clos(delegate) } まず = { it } 表示する = { println it } 平方根 = { Math.sqrt(it) } まず 100 の 平方根 を 表示する // First, show the square root of 100 // => 10.0 // source: http://d.hatena.ne.jp/uehaj/20100919/1284906117 // http://groovyconsole.appspot.com/edit/241001
- 110. ...GEP3 example DSLs 2010- 110 ©ASERT2006-2010 // source: http://d.hatena.ne.jp/uehaj/20100919/1284906117 // http://groovyconsole.appspot.com/edit/241001
- 111. Medical Prescription DSL… DSLs2010 - 111 ©ASERT2006-2010 class Drug { String name String toString() { name } } class Measure { Number number String unit, units String toString() { number == 1 ? "1 $unit" : "$number $units" } } class Quantity extends Measure {} class Duration extends Measure {} // ... http://groovyconsole.appspot.com/script/240001 by glaforge/Mihai Cazacu
- 112. …Medical Prescription DSL… DSLs2010 - 112 ©ASERT2006-2010 // ... // ---- DSL implementation ------------------------------ Integer.metaClass.getHour = {-> 1.hours } Integer.metaClass.getPill = {-> 1.pills } Integer.metaClass.getHours = {-> new Duration(number: delegate, unit: 'hour', units: 'hours') } Integer.metaClass.getPills = {-> new Quantity(number: delegate, unit: 'pill', units: 'pills') } // use the script binding for storing new drugs available as variables binding = new Binding() { def getVariable(String drug) { new Drug(name: drug) } } take = {Quantity quantity -> ['of': {Drug drug -> ['after': {Duration duration -> println "Take $quantity of $drug afer $duration" }] }] } // ...
- 113. …Medical Prescription DSL DSLs2010 - 113 ©ASERT2006-2010 // ... // ---- DSL ------------------------------- take 2.pills of chloroquinine after 6.hours http://groovyconsole.appspot.com/script/240001 by glaforge/Mihai Cazacu
- 114. Groovy DSL Features DSLs2010 - 114 ©ASERT2006-2010 Transformation
- 115. AST Transformations • Withmetaprogramming, Groovy‟s able to modify the behaviour of programs... at runtime • AST Transformations provide a compile- time approach to modify programs – AST: Abstract Syntax Tree – Ability to change what‟s being compiled at compile- time! • No runtime impact! • Lets you change the semantics of your programs! • Nice way of implementing patterns and removing boiler-plate technical code • Two kinds of transformations: global & local DSLs 2010 - 115
- 116. Better Design Patterns:Immutable... • Java Immutable Class – As per Joshua Bloch Effective Java DSLs 2010 - 116 ©ASERT2006-2010 public final class Punter { private final String first; private final String last; public String getFirst() { return first; } public String getLast() { return last; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((first == null) ? 0 : first.hashCode()); result = prime * result + ((last == null) ? 0 : last.hashCode()); return result; } public Punter(String first, String last) { this.first = first; this.last = last; } // ... // ... @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; Punter other = (Punter) obj; if (first == null) { if (other.first != null) return false; } else if (!first.equals(other.first)) return false; if (last == null) { if (other.last != null) return false; } else if (!last.equals(other.last)) return false; return true; } @Override public String toString() { return "Punter(first:" + first + ", last:" + last + ")"; } }
- 117. ...Better Design Patterns:Immutable... • Java Immutable Class – As per Joshua Bloch Effective Java DSLs 2010 - 117 ©ASERT2006-2010 public final class Punter { private final String first; private final String last; public String getFirst() { return first; } public String getLast() { return last; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((first == null) ? 0 : first.hashCode()); result = prime * result + ((last == null) ? 0 : last.hashCode()); return result; } public Punter(String first, String last) { this.first = first; this.last = last; } // ... // ... @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; Punter other = (Punter) obj; if (first == null) { if (other.first != null) return false; } else if (!first.equals(other.first)) return false; if (last == null) { if (other.last != null) return false; } else if (!last.equals(other.last)) return false; return true; } @Override public String toString() { return "Punter(first:" + first + ", last:" + last + ")"; } } boilerplate
- 118. ...Better Design Patterns:Immutable DSLs 2010 - 118 ©ASERT2006-2010 @Immutable class Punter { String first, last }
- 119. Spock DSLs 2010 -119 ©ASERT2006-2010 def "length of Spock's & his friends' names"() { expect: name.size() == length where: name | length "Spock" | 5 "Kirk" | 4 "Scotty" | 6 }
- 120. AST Builder • Numerousapproaches, still evolving. “From code” approach: • Produces: def result = new AstBuilder().buildFromCode { println "Hello World" } BlockStatement -> ReturnStatement -> MethodCallExpression -> VariableExpression("this") -> ConstantExpression("println") -> ArgumentListExpression -> ConstantExpression("Hello World") DSLs 2010 - 120
- 121. ©ASERT2006-2010 EasyB… • Description: BDD,Rspec-like testing library narrative 'segment flown', { as_a 'frequent flyer' i_want 'to accrue rewards points for every segment I fly' so_that 'I can receive free flights for my dedication to the airline' } scenario 'segment flown', { given 'a frequent flyer with a rewards balance of 1500 points' when 'that flyer completes a segment worth 500 points' then 'that flyer has a new rewards balance of 2000 points' } scenario 'segment flown', { given 'a frequent flyer with a rewards balance of 1500 points', { flyer = new FrequentFlyer(1500) } when 'that flyer completes a segment worth 500 points', { flyer.fly(new Segment(500)) } then 'that flyer has a new rewards balance of 2000 points', { flyer.pointsBalance.shouldBe 2000 } } DSLs 2010 - 121
- 122. ©ASERT2006-2010 …EasyB • Description: BDD,Rspec-like testing library examples "The number #{number}' should be converted to #{romanNumerals}", { number = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] romanNumerals = ["I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX", "X"] } scenario "Converting #number into the roman numeral #romanNumerals", { given "the number #number", { theNumber = number } when "the system converts this number to the roman numeral equivalent", { theConvertedNumber = RomanNumerals.fromInteger(theNumber) } then "the result should be #romanNumerals", { theConvertedNumber.shouldBe romanNumerals } } DSLs 2010 - 122 Source: http://www.wakaleo.com/blog/285-example-driven-testing-with-easyb
- 123. EasyB Preprocessing... • EasyBsupports either of these: • But we would like this: given ("some data") { println '... setting expectations' } Source: http://hamletdarcy.blogspot.com/2010/02/groovy-antlr-plugins-for-better-dsls.html given "some data", { println '... setting expectations' } given "some data" { println '... setting expectations' } DSLs 2010 - 123 But also consider Command Expressions (GEP-3) for Groovy1.8+.
- 124. ...EasyB Preprocessing... String addCommas(text){ def pattern = ~/(.*)(given|when|then) "([^"]*(.[^"]*)*)" {(.*)/ def replacement = /$1$2 "$3", {$4/ (text =~ pattern).replaceAll(replacement) } Source: http://hamletdarcy.blogspot.com/2010/02/groovy-antlr-plugins-for-better-dsls.html DSLs 2010 - 124 Adds the comma in where required before Groovy sees it.
- 125. ...EasyB Preprocessing class SourceModifierParserPluginextends AntlrParserPlugin { Reduction parseCST(SourceUnit sourceUnit, Reader reader) throws CompilationFailedException { def text = addCommas(reader.text) StringReader stringReader = new StringReader(text) super.parseCST(sourceUnit, stringReader) } } def parserPluginFactory = new ParserPluginFactory() { ParserPlugin createParserPlugin() { new SourceModifierParserPlugin() } } def conf = new CompilerConfiguration(pluginFactory: parserPluginFactory) def binding = ... def shell = new GroovyShell(binding, conf) Source: http://hamletdarcy.blogspot.com/2010/02/groovy-antlr-plugins-for-better-dsls.html DSLs 2010 - 125 But use with restraint as error messages will be with respect to converted source code not original.
- 126. GParsec... • Miniature parsers •Parser Combinators def isLetter = { ch -> return Character.isLetter(ch) } def isDigit = { ch -> return Character.isDigit(ch) } def letter = satisfyC(isLetter) def digit = satisfyC(isDigit) def letterAndDigit = seqC(letter, digit) assert letterAndDigit('a123###') == ['a', '1'] def identifier = seqC(identifierStart, noneOrMoreC(identifierRest)) DSLs 2010 - 126
- 127. ...GParsec... • BNF • Groovydefinitions variableDeclarator : identifier ( '=' expression )? variableDefinitions : variableDeclarator ( ',' variableDeclarator)* def variableDeclarator = seqC(identifier, optionalC(seqC(assign, expression))) def variableDefinitions = seqC(variableDeclarator, noneOrMoreC(seqC(comma, variableDeclarator))) DSLs 2010 - 127
- 128. ...GParsec • satisfyC: combinatorconsumes a single input when its predicate succeeds • altC (alt3C, altCs): is the choice combinator. Given two parsers it only looks at its second alternative if the first has not consumed any input - regardless of the final value • seqC (seq3C, seqCs): is the sequencing combinator. It runs two parsers in succession and if successful, returns the result of the two parsers • noneOrMoreC, oneOrMoreC: applies a parser zero or more times to an input stream. The result from each application of the parser are returned in a list • optionalC: The combinator optionalC may succeed in parsing some input. It always returns success. DSLs 2010 - 128
- 129. Using External Parsers DSLs2010 - 129 ©ASERT2006-2010 import static com.mdimension.jchronic.Chronic.parse def span = parse("tomorrow at 5pm") println span.endCalendar.format('yyyy-MM-dd HH:mm') // => 2010-05-19 17:00
- 130. Topics • Introduction • GroovyDSL Features A Week In The Life Of DSL INC • Summary • More Info DSLs 2010 - 130 ©ASERT2006-2010
- 131. MONDAY DSLs 2010 -131 ©ASERT2006-2010
- 132. Currency DSL… DSLs 2010- 132 ©ASERT2006-2010 From: customer@acme.org To: Guillaume Subject: Project Request Dear Guillaume, We would like a DSL for capturing currency expressions. Just US currency to start with. Thanks, Happy Customer
- 133. …Currency DSL... DSLs 2010- 133 ©ASERT2006-2010 enum Coin { penny(1), nickel(5), dime(10), quarter(25) Coin(int value) { this.value = value } int value } import static Coin.* assert 2 * quarter.value + 1 * nickel.value + 2 * penny.value == 57
- 134. …Currency DSL… DSLs 2010- 134 ©ASERT2006-2010 From: customer@acme.org To: Guillaume Subject: Project Request Dear Guillaume, That works fairly well but can we get rid of the ‘.value’ part of those expressions. They are confusing our users. Thanks, Happy Customer
- 135. ...Currency DSL... DSLs 2010- 135 ©ASERT2006-2010 class CoinMath { static multiply(Integer self, Coin c) { self * c.value } } use (CoinMath) { assert 2 * quarter + 1 * nickel + 2 * penny == 57 } // EMC equivalent Integer.metaClass.multiply = { Coin c -> delegate * c.value } assert 2 * quarter + 1 * nickel + 2 * penny == 57
- 136. …Currency DSL… DSLs 2010- 136 ©ASERT2006-2010 From: customer@acme.org To: Guillaume Subject: Project Request Dear Guillaume, Much better but our users are sometimes using plural as well as singular expressions. Is there anything that you can do about that? Thanks, Happy Customer
- 137. ... Currency DSL DSLs2010 - 137 ©ASERT2006-2010 class CoinValues { static get(Integer self, String name) { self * Coin."${singular(name)}".value } static singular(String val) { val.endsWith('ies') ? val[0..-4] + 'y' : val.endsWith('s') ? val[0..-2] : val } } use (CoinValues) { assert 2.quarters + 1.nickel + 2.pennies == 57 } // EMC equivalent Integer.metaClass.getProperty = { String name -> def mp = Integer.metaClass.getMetaProperty(name) if (mp) return mp.getProperty(delegate) def singular = name.endsWith('ies') ? name[0..-4] + 'y' : name.endsWith('s') ? name[0..-2] : name delegate * Coin."$singular".value } assert 2.quarters + 1.nickel + 2.pennies == 57
- 138. TUESDAY DSLs 2010 -138 ©ASERT2006-2010 http://www.google.com/imgres?imgurl=http://i733.photobucket.com/albums/ww336/snake1953/Day_of_Week/Tue/HappyTuesda
- 139. Business logic DSL… DSLs2010 - 139 ©ASERT2006-2010 From: customer@acme.org To: Paul King Subject: Project Request Dear Paul, Could you please create us a small DSL for capturing our business rules. We are thinking of something like: price = 3 quantity = 10 total = price * quantity Perhaps also an ability to check values: assert total == 30 Thanks, Happy Customer P.S. Will send a couple of more details in a follow-up email but please consider the requirements as being pretty much locked down.
- 140. …Business logic DSL… •Options – Embedded Groovy – Regex parser – Antlr parser – Split / StringTokenizer – Parser combinators • … Many options, details not important … DSLs 2010 - 140 ©ASERT2006-2010
- 141. … Business logicDSL … DSLs 2010 - 141 ©ASERT2006-2010 From: customer@acme.org To: Paul King Subject: Project Request Date: Mid morning Dear Paul, We were thinking a bit more about it, and it would be good to have just a few more features. Hopefully, they won’t have much impact on your existing design and can be added very quickly. It isn’t much, just the ability to have IF, THEN, ELSE like structures, oh yeah and the ability to have loops, and store stuff in files and get stuff from databases and web services if we need. Thanks, Happy Customer P.S. It would be great if you can be finished by this afternoon. We have a customer who would like this feature RSN. Thanks.
- 142. … Business logicDSL … DSLs 2010 - 142 ©ASERT2006-2010 def shell = new GroovyShell() shell.evaluate(''' price = 3 quantity = 10 total = price * quantity assert total == 30 ''')
- 143. … Business logicDSL … DSLs 2010 - 143 ©ASERT2006-2010 From: customer@acme.org To: Paul King Subject: Project Request Date: This afternoon Dear Paul, We were really happy with the DSL engine you provided us with but people started importing all sorts of classes. Can you stop them from doing that? Maybe just java.lang.Math only. Also we decided we don’t like ‚while‛ loops anymore. Leave you to it. Thanks, Happy Customer P.S. Have a beer and crab dinner for me at the conference. Bye.
- 144. … Business logicDSL … DSLs 2010 - 144 ©ASERT2006-2010 class CustomerShell { Object evaluate(String text) { try { def loader = new CustomerClassLoader() def clazz = loader.parseClass(text) def script = clazz.newInstance() return script.run() } catch (...) { ... } } } class CustomerClassLoader extends GroovyClassLoader { def createCompilationUnit(CompilerConfiguration config, CodeSource codeSource) { CompilationUnit cu = super.createCompilationUnit(config, codeSource) cu.addPhaseOperation(new CustomerFilteringNodeOperation(), Phases.SEMANTIC_ANALYSIS) return cu } } private class CustomerFilteringNodeOperation extends PrimaryClassNodeOperation { // ... private static final allowedStaticImports = [Math].asImmutable() void visitStaticMethodCallExpression(StaticMethodCallExpression smce) { if (!allowedStaticImports.contains(smce.ownerType.getTypeClass())) { throw new SecurityException("Static method call expressions forbidden in acme shell.") } } void visitWhileLoop(WhileStatement whileStatement) { throw new SecurityException("While statements forbidden in acme shell.") } // ... } Please also see the ArithmeticShell which is included under examples in the Groovy distribution
- 145. … Business logicDSL DSLs 2010 - 145 ©ASERT2006-2010 def shell = new CustomerShell() shell.evaluate(''' price = 3 quantity = 10 total = price * quantity assert total == 30 ''')
- 146. WEDNESDAY DSLs 2010 -146 ©ASERT2006-2010 http://www.crystalscomments.com/1/days/wednesday/animals/006.jpg
- 147. Stock Exchange OrderDSL… DSLs 2010 - 147 ©ASERT2006-2010 Example inspired from DSLs in Action: http://www.manning.com/ghosh/ From: customer@finance-broker.org To: Guillaume Subject: Project Request Date: Wednesday morning Dear Guillaume, For our order processing system we have a need to capture client orders using a DSL. An order includes the name of the security to be transacted (buy or sell) as well as quantity and unit price details to specify any constraint that the counterparty would like to impose on the price of transaction. Thanks, Happy Customer
- 148. … Stock ExchangeOrder DSL… DSLs 2010 - 148 ©ASERT2006-2010 // ----- Implementation of the Fluent API ----- enum Action { Buy, Sell } class Order { def security def quantity, limitPrice boolean allOrNone def valueCalculation Action action def buy(Integer quantity, String security) { this.quantity = quantity this.security = security this.action = Action.Buy return this } def sell(Integer quantity, String security) { this.quantity = quantity this.security = security this.action = Action.Sell return this } def limitPrice(Integer limit) { this.limitPrice = limit; return this } def allOrNone(boolean allOrNone) { this.allOrNone = allOrNone; return this } def valueAs(Closure valueCalculation) { this.valueCalculation = valueCalculation; return this } String toString() { "$action $quantity shares of $security at valuation of ${valueCalculation(quantity, limitPrice)}" } } println new Order() .sell(150, "IBM") .limitPrice(300) .allOrNone(true) .valueAs{ qty, unitPrice -> qty * unitPrice - 100 } println new Order() .buy(200, "GOOG") .limitPrice(200) .allOrNone(true) .valueAs{ qty, unitPrice -> qty * unitPrice - 500 } Sell 150 shares of IBM at valuation of 44900 Buy 200 shares of GOOG at valuation of 39500
- 149. …Stock Exchange OrderDSL… DSLs 2010 - 149 ©ASERT2006-2010 From: customer@finance-broker.org To: Guillaume Subject: Project Request Date: Wednesday morning Dear Guillaume, That version was great but can you make the DSL a little more fluent. The brokers aren’t programmers after all! Thanks, Happy Customer
- 150. …Stock Exchange OrderDSL… DSLs 2010 - 150 ©ASERT2006-2010 class Order { def security def quantity def limitPrice def allOrNone def value def bs def buy(securityQuantity, closure) { bs = 'Bought' buySell(securityQuantity, closure) } def sell(securityQuantity, closure) { bs = 'Sold' buySell(securityQuantity, closure) } private buySell(securityQuantity, closure) { // multiple assignment (security, quantity) = [securityQuantity.security, securityQuantity.quantity] // better clone the closure to avoid multi-threading access issues def c = closure.clone() // delegate the method calls inside the closure to our methodMissing c.delegationStrategy = Closure.DELEGATE_ONLY c.delegate = this def valuation = c() println "$bs $quantity $security.name at valuation of $valuation" } // methods inside the closure will assign the Order properties def methodMissing(String name, args) { this."$name" = args[0] } ...
- 151. …Stock Exchange OrderDSL… DSLs 2010 - 151 ©ASERT2006-2010 ... def getTo() { this } def valueAs(closure) { value = closure(quantity, limitPrice) } } class Security { String name } class Quantity { Security security Integer quantity } Integer.metaClass.getShares = { -> delegate } Integer.metaClass.of = { new Quantity(security: it, quantity: delegate) } class CustomBinding extends Binding { def getVariable(String symbol) { // create a new order each time // for when you pass several orders if (symbol == "newOrder") new Order() // otherwise, it's an instrument // trick to avoid using strings: use IBM instead of 'IBM' else new Security(name: symbol) } } // use the script binding for retrieving IBM, etc. binding = new CustomBinding() newOrder.to.buy(100.shares.of(IBM)) { limitPrice 300 allOrNone true valueAs { qty, unitPrice -> qty * unitPrice - 200 } } newOrder.to.sell 200.shares.of(GOOG), { limitPrice 200 allOrNone false valueAs { qty, unitPrice -> qty * unitPrice - 500 } }
- 152. …Stock Exchange OrderDSL… DSLs 2010 - 152 ©ASERT2006-2010 From: customer@finance-broker.org To: Guillaume Subject: Project Request Date: Wednesday lunch time Dear Guillaume, That version was great but can we simplify the constraint to remove the parameters, i.e.: change { qty, unitPrice -> qty * unitPrice - 200 } to this: { qty * unitPrice - 200 } Thanks, Happy Customer
- 153. …Stock Exchange OrderDSL… DSLs 2010 - 153 ©ASERT2006-2010 class Order { ... def allOrNone def valueCalculation def bs ... private buySell(securityQuantity, closure) { ... valueCalculation = c() // debug print resulting order println toString() return this } ... def valueAs(Closure wrapee) { // in order to be able to define closures like { qty * unitPrice } without having // to explicitly pass the parameters to the closure we can wrap the closure inside // another one and that closure sets a delegate to the qty and unitPrice variables def wrapped = { qty, unitPrice -> def cloned = wrapee.clone() cloned.resolveStrategy = Closure.DELEGATE_ONLY cloned.delegate = [qty: qty, unitPrice: unitPrice] cloned() } return wrapped } String toString() { "$bs $quantity shares of $security.name and valuation of ${valueCalculation(quantity, limitPrice)}" } } newOrder.to.buy(100.shares.of(IBM)) { limitPrice 300 allOrNone true valueAs { qty * unitPrice - 500 } } newOrder.to.sell 200.shares.of(GOOG), { limitPrice 200 allOrNone false valueAs { qty * unitPrice - 100 } }
- 154. …Stock Exchange OrderDSL… DSLs 2010 - 154 ©ASERT2006-2010 From: customer@finance-broker.org To: Guillaume Subject: Project Request Date: Wednesday afternoon Dear Guillaume, Fantastic! This is getting better all the time! But can we get rid most of the ‘.’ and bracket symbols! Thanks, Happy Customer
- 155. …Stock Exchange OrderDSL… DSLs 2010 - 155 ©ASERT2006-2010 // Characteristics of the order: "of GOOG {...}" def of(SecurityAndCharacteristics secAndCharact) { security = secAndCharact.security def c = secAndCharact.characteristics.clone() c.delegationStrategy = Closure.DELEGATE_ONLY c.delegate = this c() // debug print of the resulting order println toString() return this } // Valuation closure: "of { qty, unitPrice -> ... }" def of(Closure valueCalculation) { // in order to be able to define closures like { qty * unitPrice } // without having to explicitly pass the parameters to the closure // we can wrap the closure inside another one // and that closure sets a delegate to the qty and unitPrice variables def wrapped = { qty, unitPrice -> def cloned = valueCalculation.clone() cloned.resolveStrategy = Closure.DELEGATE_ONLY cloned.delegate = [qty: qty, unitPrice: unitPrice] cloned() } return wrapped } String toString() { "$action $quantity shares of $security.name at limit price of $limitPrice" } } // ... http://groovyconsole.appspot.com/script/226001 by glaforge
- 156. …Stock Exchange OrderDSL… DSLs 2010 - 156 ©ASERT2006-2010 // ... class Security { String name } class SecurityAndCharacteristics { Security security Closure characteristics } class CustomBinding extends Binding { def getVariable(String word) { // return System.out when the script requests to write to 'out' if (word == "out") System.out // don't thrown an exception and return null // when a silent sentence word is used, // like "to" and "the" in our DSL null } } // Script helper method for "GOOG {}", "VMW {}", etc. def methodMissing(String name, args) { new SecurityAndCharacteristics( security: new Security(name: name), characteristics: args[0] ) } // Script helper method to make "order to" silent // by just creating our current order def order(to) { new Order() } // use the script binding for silent sentence words like "to", "the" binding = new CustomBinding() // syntax for 200.shares Integer.metaClass.getShares = { -> delegate }
- 157. …Stock Exchange OrderDSL… DSLs 2010 - 157 ©ASERT2006-2010 // ---- Stock exchange orders DSL ---- order to buy 200.shares of GOOG { limitPrice 500 allOrNone false at the value of { qty * unitPrice - 100 } } order to sell 150.shares of VMW { limitPrice 80 allOrNone true at the value of { qty * unitPrice } } http://groovyconsole.appspot.com/script/226001 by glaforge
- 158. …Stock Exchange OrderDSL DSLs 2010 - 158 ©ASERT2006-2010 From: customer@finance-broker.org To: Guillaume Subject: Project Request Date: Wednesday evening Dear Guillaume, Brilliant! Even our CEO could write orders! Thanks, Happy Customer
- 159. THURSDAY DSLs 2010 -159 ©ASERT2006-2010 http://t1.gstatic.com/images?q=tbn:_VBloEP8YC-6IM:http://msp248.photobucket.com/albums/gg171/ingrid2002/TextPL252028
- 160. Einstein‟s Riddle DSL… DSLs 2010 - 160 ©ASERT2006-2010 From: customer@acme.org To: Paul King Subject: Project Request Date: Early morning Dear Paul, We would like a DSL for capturing our business rules. Our business rules are captured in the form of logic clauses. They are very much like those found in Einstein’s riddle. Thanks, Happy Customer
- 161. Einstein‟s Riddle… • Wikipedia:The zebra puzzle is a well- known logic puzzle – It is often called Einstein's Puzzle or Einstein's Riddle because it is said to have been invented by Albert Einstein as a boy, with the claim that Einstein said “only 2 percent of the world's population can solve it.” – The puzzle is also sometimes attributed to Lewis Carroll. However, there is no known evidence for Einstein's or Carroll's authorship; and the original puzzle cited below mentions brands of cigarette, such as Kools, that did not exist during Carroll's lifetime or Einstein's boyhood DSLs 2010 - 161 ©ASERT2006-2010
- 162. …Einstein‟s Riddle DSLs 2010- 162 ©ASERT2006-2010 • Some premises: – The British person lives in the red house – The Swede keeps dogs as pets – The Dane drinks tea – The green house is on the left of the white house – The green homeowner drinks coffee – The man who smokes Pall Mall keeps birds – The owner of the yellow house smokes Dunhill – The man living in the center house drinks milk – The Norwegian lives in the first house – The man who smokes Blend lives next to the one who keeps cats – The man who keeps the horse lives next to the man who smokes Dunhill – The man who smokes Bluemaster drinks beer – The German smokes Prince – The Norwegian lives next to the blue house – The man who smokes Blend has a neighbor who drinks water • And a question: – Who owns the fish?
- 163. Einstein‟s Riddle :Prolog ©ASERT2006-2010 % from http://www.baptiste-wicht.com/2010/09/solve-einsteins-riddle-using-prolog % Preliminary definitions persons(0, []) :- !. persons(N, [(_Men,_Color,_Drink,_Smoke,_Animal)|T]) :- N1 is N-1, persons(N1,T). person(1, [H|_], H) :- !. person(N, [_|T], R) :- N1 is N-1, person(N1, T, R). % The Brit lives in a red house hint1([(brit,red,_, _, _)|_]). hint1([_|T]) :- hint1(T). % The Swede keeps dogs as pets hint2([(swede,_,_,_,dog)|_]). hint2([_|T]) :- hint2(T). % The Dane drinks tea hint3([(dane,_,tea,_,_)|_]). hint3([_|T]) :- hint3(T). % The Green house is on the left of the White house hint4([(_,green,_,_,_),(_,white,_,_,_)|_]). hint4([_|T]) :- hint4(T). % The owner of the Green house drinks coffee. hint5([(_,green,coffee,_,_)|_]). hint5([_|T]) :- hint5(T). ... DSLs 2010 - 163
- 164. Einstein‟s Riddle DSL… DSLs 2010 - 164 ©ASERT2006-2010 From: customer@acme.org To: Paul King Subject: Project Request Date: Early morning Dear Paul, Thanks for your Prolog solution but we don’t have Prolog installed. Do you have a version that runs on the JVM? Thanks, Happy Customer
- 165. Einstein‟s Riddle :Polyglot ©ASERT2006-2010 @GrabResolver('http://dev.inf.unideb.hu:8090/archiva/repository/internal') //@Grab('jlog:jlogic-debug:1.3.6') @Grab('org.prolog4j:prolog4j-api:0.2.0') // uncomment one of the next three lines //@Grab('org.prolog4j:prolog4j-jlog:0.2.0') @Grab('org.prolog4j:prolog4j-tuprolog:0.2.0') //@Grab('org.prolog4j:prolog4j-jtrolog:0.2.0') import org.prolog4j.* def p = ProverFactory.prover p.addTheory(new File('/GroovyExamples/tuProlog/src/einstein.pl').text) def sol = p.solve("solution(Persons).") //println sol.solution.get('Persons') // jlog to avoid converter println sol.get('Persons') // jtrolog/tuProlog DSLs 2010 - 165
- 166. Einstein‟s Riddle DSL… DSLs 2010 - 166 ©ASERT2006-2010 From: customer@acme.org To: Paul King Subject: Project Request Date: Early morning Dear Paul, Thanks for that version but in terms of maintaining the rules, we would like a more fluent expression of the rules rather than Prolog? Any thoughts? Thanks, Happy Customer
- 167. Einstein‟s Riddle :Polyglot w/ DSL… ©ASERT2006-2010 // define some domain classes and objects enum Pet { dog, cat, bird, fish, horse } enum Color { green, white, red, blue, yellow } enum Smoke { dunhill, blends, pallmall, prince, bluemaster } enum Drink { water, tea, milk, coffee, beer } enum Nationality { Norwegian, Dane, Brit, German, Swede } dogs = dog; birds = bird; cats = cat; horses = horse a = owner = house = the = abode = person = man = is = to = side = next = who = different = 'ignored' DSLs 2010 - 167 // some preliminary definitions p = ProverFactory.prover hintNum = 1 p.addTheory(''' persons(0, []) :- !. persons(N, [(_Men,_Color,_Drink,_Smoke,_Animal)|T]) :- N1 is N-1, persons(N1,T). person(1, [H|_], H) :- !. person(N, [_|T], R) :- N1 is N-1, person(N1, T, R). ''')
- 168. …Einstein‟s Riddle :Polyglot w/ DSL… ©ASERT2006-2010 DSLs 2010 - 168 // define some helper methods (our interface to prolog) def addPairHint(Map m) { def from = m.from?.toString()?.toLowerCase() p.addTheory(""" hint$hintNum([(${from ?: '_'},${m.color ?: '_'},${m.drink ?: '_'},${m.smoke ?: '_'},${m.pet ?: '_'})|_]). hint$hintNum([_|T]) :- hint$hintNum(T). """) hintNum++ } def addPositionHint(Map m, int pos) { def from = m.from?.toString()?.toLowerCase() p.addTheory(""" hint$hintNum(Persons) :- person($pos, Persons, (${from ?: '_'},${m.color ?: '_'},${m.drink ?: '_'},${m.smoke ?: '_'},${m.pet ?: '_'})). """) hintNum++ } def addToLeftHint(Map left, Map right) { p.addTheory(""" hint$hintNum([(_,$left.color,_,_,_),(_,$right.color,_,_,_)|_]). hint$hintNum([_|T]) :- hint$hintNum(T). """) hintNum++ } ...
- 169. …Einstein‟s Riddle :Polyglot w/ DSL… ©ASERT2006-2010 DSLs 2010 - 169 // now implement DSL in terms of helper methods def the(Nationality n) { def ctx = [from:n] [ drinks: { d -> addPairHint(ctx + [drink:d]) }, smokes: { s -> addPairHint(ctx + [smoke:s]) }, keeps: { p -> addPairHint(ctx + [pet:p]) }, rears: { p -> addPairHint(ctx + [pet:p]) }, owns:{ _the -> [first:{ house -> addPositionHint(ctx, 1) }] }, has:{ _a -> [pet: { a -> addPairHint(ctx + [pet:a]) }] + Color.values().collectEntries{ c -> [c.toString(), { _dummy -> addPairHint(ctx + [color:c]) } ] } }, lives: { _next -> [to: { _the -> Color.values().collectEntries{ c -> [c.toString(), { _dummy -> addNeighbourHint(ctx, [color:c]) } ] } }]} ] } ...
- 170. …Einstein‟s Riddle :Polyglot w/ DSL… ©ASERT2006-2010 DSLs 2010 - 170 // now define the DSL the man from the centre house drinks milk the Norwegian owns the first house the Dane drinks tea the German smokes prince the Swede keeps dogs // alternate ending: has a pet dog the Brit has a red house // alternate ending: red abode the owner of the green house drinks coffee the owner of the yellow house smokes dunhill the person known to smoke pallmall rears birds // alt’n8 end: keeps birds the man known to smoke bluemaster drinks beer the green house is on the left side of the white house the man known to smoke blends lives next to the one who keeps cats the man known to keep horses lives next to the man who smokes dunhill the man known to smoke blends lives next to the one who drinks water the Norwegian lives next to the blue house
- 171. Einstein‟s Riddle DSL… DSLs 2010 - 171 ©ASERT2006-2010 From: customer@acme.org To: Paul King Subject: Project Request Date: Early morning Dear Paul, That’s great. We even get some code completion When using an IDE. Is there anything more we can do to get more completion? Thanks, Happy Customer
- 172. …Einstein‟s Riddle :Polyglot w/ DSL… ©ASERT2006-2010 DSLs 2010 - 172 // now implement DSL in terms of helper methods def the(Nationality n) { def ctx = [from:n] [ drinks: { d -> addPairHint(ctx + [drink:d]) }, smokes: { s -> addPairHint(ctx + [smoke:s]) }, keeps: { p -> addPairHint(ctx + [pet:p]) }, ... ] } ... the German smokes prince the(German).smokes(prince) n = German ctx = [from: German] [drinks: …, smokes: { s -> addPairHint([from: German, smoke: s]) }, keeps: …, … ] addPairHint([from: German, smoke: prince])
- 173. …Einstein‟s Riddle :Polyglot w/ DSL… • Some parts of our DSL are automatically statically inferred, e.g. typing „bl‟ and then asking for completion yields: • But other parts are not known, e.g. the word „house‟ in the fragment below: DSLs 2010 - 173 ©ASERT2006-2010 „house‟ is key for a Map and could be any value
- 174. …Einstein‟s Riddle :Polyglot w/ DSL ©ASERT2006-2010 DSLs 2010 - 174 class HousePlaceHolder { def c1, script def house(_is) { [on: { _the -> [left: { _side -> [of: { __the -> Color.values().collectEntries { c2 -> [c2.toString(), { _dummy -> script.addToLeftHint( [color: c1], [color: c2] )}]} }]}]}] } } def the(Color c1) { new HousePlaceHolder(c1:c1, script:this) } def the(Color c1) {[ house: { _is -> [on: { _the -> [left: { _side -> [of: { __the -> Color.values().collectEntries{ c2 -> [c2.toString(), { _dummy -> addToLeftHint([color:c1], [color:c2]) }]} }]}]}]} ]} „house‟ is now understood
- 175. Einstein‟s Riddle DSL… DSLs 2010 - 175 ©ASERT2006-2010 From: customer@acme.org To: Paul King Subject: Project Request Date: Early morning Dear Paul, That’s fantastic! But we have just started standardizing on Choco as our logic solving engine. I guess we need to start from scratch. Let me know what you think. Thanks, Happy Customer
- 176. Einstein‟s Riddle :Choco w/ DSL… ©ASERT2006-2010 DSLs 2010 - 176 @GrabResolver('http://www.emn.fr/z-info/choco-solver/mvn/repository/') @Grab('choco:choco:2.1.1-SNAPSHOT') import static choco.Choco.* import choco.kernel.model.variables.integer.* def m = new choco.cp.model.CPModel() m.metaClass.plus = { m.addConstraint(it); m } def s = new choco.cp.solver.CPSolver() choco.Choco.metaClass.static.eq = { c, v -> delegate.eq(c, v.ordinal()) } def makeEnumVar(st, arr) { choco.Choco.makeIntVar(st, 0, arr.size()-1, choco.Options.V_ENUM) } pets = new IntegerVariable[num] colors = new IntegerVariable[num] smokes = new IntegerVariable[num] drinks = new IntegerVariable[num] nations = new IntegerVariable[num] (0..<num).each { i -> pets[i] = makeEnumVar("pet$i", pets) colors[i] = makeEnumVar("color$i", colors) smokes[i] = makeEnumVar("smoke$i", smokes) drinks[i] = makeEnumVar("drink$i", drinks) nations[i] = makeEnumVar("nation$i", nations) } ...
- 177. …Einstein‟s Riddle :Choco w/ DSL… ©ASERT2006-2010 DSLs 2010 - 177 // define DSL (simplistic non-refactored version) def neighbours(var1, val1, var2, val2) { and( ifOnlyIf(eq(var1[0], val1), eq(var2[1], val2)), implies(eq(var1[1], val1), or(eq(var2[0], val2), eq(var2[2], val2))), implies(eq(var1[2], val1), or(eq(var2[1], val2), eq(var2[3], val2))), implies(eq(var1[3], val1), or(eq(var2[2], val2), eq(var2[4], val2))), ifOnlyIf(eq(var1[4], val1), eq(var2[3], val2)) ) } iff = { e1, c1, e2, c2 -> and(*(0..<num).collect{ ifOnlyIf(eq(e1[it], c1), eq(e2[it], c2)) }) } ... // define the DSL in terms of DSL implementation def the(Nationality n) { def ctx = [nations, n] [ drinks:iff.curry(*ctx, drinks), smokes:iff.curry(*ctx, smokes), keeps:iff.curry(*ctx, pets), rears:iff.curry(*ctx, pets), owns:{ _the -> [first:{ house -> eq(nations[first], n)}] }, ...
- 178. …Einstein‟s Riddle :Choco w/ DSL… ©ASERT2006-2010 DSLs 2010 - 178 // define rules m += all pets are different m += all colors are different m += all smokes are different m += all drinks are different m += all nations are different m += the man from the centre house drinks milk m += the Norwegian owns the first house m += the Dane drinks tea m += the German smokes prince m += the Swede keeps dogs // alternate ending: has a pet dog m += the Brit has a red house // alternate ending: red abode m += the owner of the green house drinks coffee m += the owner of the yellow house smokes dunhill m += the person known to smoke pallmall rears birds // alt end: keeps birds m += the man known to smoke bluemaster drinks beer m += the green house is on the left side of the white house m += the man known to smoke blends lives next to the one who keeps cats m += the man known to keep horses lives next to the man who smokes dunhill m += the man known to smoke blends lives next to the one who drinks water m += the Norwegian lives next to the blue house ...
- 179. …Einstein‟s Riddle :Choco w/ DSL • Output: DSLs 2010 - 179 ©ASERT2006-2010 def pretty(s, c, arr, i) { c.values().find{ it.ordinal() == s.getVar(arr[i])?.value } } // invoke logic solver s.read(m) def more = s.solve() while (more) { for (i in 0..<num) { print 'The ' + pretty(s, Nationality, nations, i) print ' has a pet ' + pretty(s, Pet, pets, i) print ' smokes ' + pretty(s, Smoke, smokes, i) print ' drinks ' + pretty(s, Drink, drinks, i) println ' and lives in a ' + pretty(s, Color, colors, i) + ' house' } more = s.nextSolution() } Solving Einstein's Riddle: The Norwegian has a pet cat smokes dunhill drinks water and lives in a yellow house The Dane has a pet horse smokes blends drinks tea and lives in a blue house The Brit has a pet bird smokes pallmall drinks milk and lives in a red house The German has a pet fish smokes prince drinks coffee and lives in a green house The Swede has a pet dog smokes bluemaster drinks beer and lives in a white house
- 180. FRIDAY DSLs 2010 -180 ©ASERT2006-2010 http://t3.gstatic.com/images?q=tbn:mgkj1lXpQ2-uWM:http://i298.photobucket.com/albums/mm269/bearyjuicylicious/comments
- 181. Important business meetingsall afternoon! DSLs 2010 - 181 ©ASERT2006-2010 http://www.flickr.com/photos/bobswanson/5093775403/sizes/l/in/pool-52240148330@N01/
- 182. Topics • Introduction • GroovyDSL Features • A Week In The Life Of DSL INC Summary • More Info DSLs 2010 - 182 ©ASERT2006-2010
- 183. Some Finishing Guidelines •Language and program evolve together … In the end your program will look as if the language had been designed for it … you end up with code which is clear, small, and efficient. – Paul Graham • Don‟t think just about Coding up your DSL – But also about its target audience, its evolution, required tool support and its testability DSLs 2010 - 183
- 184. Start small, withkey concepts Beware over-engineering!
- 185.
- 186. Get your handsdirty Play with the end-users
- 187. Let your DSLfly, it‟s not yours, it‟s theirs!
- 188.
- 189. Stay humble, You can‟tget it right the 1st time. Don‟t design alone at your desk Involve the end users from the start
- 190. Playing it safein a sandbox
- 191. Topics • Introduction • GroovyDSL Features • A Week In The Life Of DSL INC • Summary More Info DSLs 2010 - 191 ©ASERT2006-2010
- 192. Further Info… DSLs 2010- 192 ©ASERT2006-2010 • Compilers : Principles, Techniques, and Tools/ Edition 2, Alfred Aho, Ravi Sethi, Jeffrey Ullman, Monica Lam • Practical API Design : Confessions of a Java Framework Architect, Jaroslav Tulach • Language Implementation Patterns : Create Your Own Domain-Specific and General Programming Languages, Terence Parr
- 193. …Further Info DSLs 2010- 193 ©ASERT2006-2010 • A model-driven framework for domain specific languages, Martin Karlsch • Design Guidelines for Domain Specific Languages, Gabor Karsai et al • Program Comprehension for Domain- Specific Languages, Pereira et al • Diagrammatic Representations in Domain- Specific Languages, Konstantinos Tourlas • DSLs in Action, Debasish Ghosh • Domain-Specific Languages, Martin Fowler • DSLs in Boo : Domain Specific Languages in .NET, Ayende Rahien
- 194. GinA 2ed “ReGinA”is coming! DSLs 2010 - 194 Contains a chapter on DSLs!