SlideShare a Scribd company logo
METAPROGRAMMING
OPTIONS WITH GROOVY
METAPROGRAMMING
OPTIONS WITH GROOVY
Iván López @ilopmarIván López @ilopmar@LondonGGUG@LondonGGUG
Hello!
I am Iván López
@ilopmar
http://greachconf.com@madridgug
▷ 1st
rule: You DO talk about the
London-GGUG
▷ 2nd
rule: If it's your first London-
GGUG you HAVE to talk
▷3rd
rule: You have to be awesome
(by David Dawson)
London-GGUG rules
Groovy is dynamic
▷ “Delay” to runtime some decisions
▷ Add properties/behaviours in
runtime
▷ Wide range of applicability
What is
metaprogramming?
“Metaprogramming is the writing
of computer programs that write
or manipulate other programs (or
themselves) as their data.
- Wikipedia
1.
Runtime
metaprogramming
Runtime metaprogramming
▷ Groovy provides this through Meta-
Object Protocol (MOP)
▷ Use MOP to:
– Invoke methods dynamically
– Synthesize classes and methods on
the fly
What is the Meta Object Protocol?
Groovy
Groovy
Java
Java
MOP
MetaClass
▷ MetaClass registry for each class
▷ Collection of methods/properties
▷ We can always modify the metaclass
MOP method
injection
MOP Method Injection
▷ Injecting methods at code-writing time
▷ We can “open” a class any time
▷ Different techniques:
– MetaClass
– Categories
– Extensions
– Mixins vs Traits
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
String chuckIpsum = "If you can see Chuck Norris, he can see you.
If you can not see Chuck Norris you may be only seconds away from death"
println StringUtils.truncate(chuckIpsum, 72)
println StringUtils.truncate(chuckIpsum, 72, true)
// Execution
If you can see Chuck Norris, he can see you. If you can not see Chuck No
If you can see Chuck Norris, he can see you. If you can not see Chuck No...
String.metaClass.truncate = { Integer length, Boolean overflow = false ->
delegate.take(length) + (overflow ? '...' : '')
}
assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true)
Adding methods using MetaClass
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
String chuckIpsum = "If you can see Chuck Norris, he can see you.
If you can not see Chuck Norris you may be only seconds away from death"
println StringUtils.truncate(chuckIpsum, 72)
println StringUtils.truncate(chuckIpsum, 72, true)
// Execution
If you can see Chuck Norris, he can see you. If you can not see Chuck No
If you can see Chuck Norris, he can see you. If you can not see Chuck No...
String.metaClass.truncate = { Integer length, Boolean overflow = false ->
delegate.take(length) + (overflow ? '...' : '')
}
assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true)
Adding methods using MetaClass
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
String chuckIpsum = "If you can see Chuck Norris, he can see you.
If you can not see Chuck Norris you may be only seconds away from death"
println StringUtils.truncate(chuckIpsum, 72)
println StringUtils.truncate(chuckIpsum, 72, true)
// Execution
If you can see Chuck Norris, he can see you. If you can not see Chuck No
If you can see Chuck Norris, he can see you. If you can not see Chuck No...
String.metaClass.truncate = { Integer length, Boolean overflow = false ->
delegate.take(length) + (overflow ? '...' : '')
}
assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true)
Adding methods using MetaClass
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
String chuckIpsum = "If you can see Chuck Norris, he can see you.
If you can not see Chuck Norris you may be only seconds away from death"
println StringUtils.truncate(chuckIpsum, 72)
println StringUtils.truncate(chuckIpsum, 72, true)
// Execution
If you can see Chuck Norris, he can see you. If you can not see Chuck No
If you can see Chuck Norris, he can see you. If you can not see Chuck No...
String.metaClass.truncate = { Integer length, Boolean overflow = false ->
delegate.take(length) + (overflow ? '...' : '')
}
assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true)
Adding methods using MetaClass
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
String chuckIpsum = "If you can see Chuck Norris, he can see you.
If you can not see Chuck Norris you may be only seconds away from death"
println StringUtils.truncate(chuckIpsum, 72)
println StringUtils.truncate(chuckIpsum, 72, true)
// Execution
If you can see Chuck Norris, he can see you. If you can not see Chuck No
If you can see Chuck Norris, he can see you. If you can not see Chuck No...
String.metaClass.truncate = { Integer length, Boolean overflow = false ->
delegate.take(length) + (overflow ? '...' : '')
}
assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true)
Adding methods using MetaClass
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
String chuckIpsum = "If you can see Chuck Norris, he can see you.
If you can not see Chuck Norris you may be only seconds away from death"
println StringUtils.truncate(chuckIpsum, 72)
println StringUtils.truncate(chuckIpsum, 72, true)
// Execution
If you can see Chuck Norris, he can see you. If you can not see Chuck No
If you can see Chuck Norris, he can see you. If you can not see Chuck No...
String.metaClass.truncate = { Integer length, Boolean overflow = false ->
delegate.take(length) + (overflow ? '...' : '')
}
assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true)
Adding methods using MetaClass
class Utils {
}
def utilsInstance = new Utils()
Utils.metaClass.version = "3.0"
utilsInstance.metaClass.released = true
assert utilsInstance.version == "3.0"
assert utilsInstance.released == true
Adding properties using MetaClass
Adding properties using MetaClass
class Utils {
}
def utilsInstance = new Utils()
Utils.metaClass.version = "3.0"
utilsInstance.metaClass.released = true
assert utilsInstance.version == "3.0"
assert utilsInstance.released == true
class Utils {
}
def utilsInstance = new Utils()
Utils.metaClass.version = "3.0"
utilsInstance.metaClass.released = true
assert utilsInstance.version == "3.0"
assert utilsInstance.released == true
Adding properties using MetaClass
class Utils {
}
def utilsInstance = new Utils()
Utils.metaClass.version = "3.0"
utilsInstance.metaClass.released = true
assert utilsInstance.version == "3.0"
assert utilsInstance.released == true
Adding properties using MetaClass
// Integer
assert '42' == 42.toString()
Integer.metaClass.toString = {
delegate == 42 ?
'The answer to life, the universe and everything' :
String.valueOf(delegate)
}
assert 42.toString() == 'The answer to life, the universe and everything'
assert 100.toString() == '100'
// Boolean
assert false.toBoolean() == false
Boolean.metaClass.toBoolean = { !delegate }
assert false.toBoolean() == true
Overriding methods using MetaClass
// Integer
assert '42' == 42.toString()
Integer.metaClass.toString = {
delegate == 42 ?
'The answer to life, the universe and everything' :
String.valueOf(delegate)
}
assert 42.toString() == 'The answer to life, the universe and everything'
assert 100.toString() == '100'
// Boolean
assert false.toBoolean() == false
Boolean.metaClass.toBoolean = { !delegate }
assert false.toBoolean() == true
Overriding methods using MetaClass
// Integer
assert '42' == 42.toString()
Integer.metaClass.toString = {
delegate == 42 ?
'The answer to life, the universe and everything' :
String.valueOf(delegate)
}
assert 42.toString() == 'The answer to life, the universe and everything'
assert 100.toString() == '100'
// Boolean
assert false.toBoolean() == false
Boolean.metaClass.toBoolean = { !delegate }
assert false.toBoolean() == true
Overriding methods using MetaClass
// Integer
assert '42' == 42.toString()
Integer.metaClass.toString = {
delegate == 42 ?
'The answer to life, the universe and everything' :
String.valueOf(delegate)
}
assert 42.toString() == 'The answer to life, the universe and everything'
assert 100.toString() == '100'
// Boolean
assert false.toBoolean() == false
Boolean.metaClass.toBoolean = { !delegate }
assert false.toBoolean() == true
Overriding methods using MetaClass
// Integer
assert '42' == 42.toString()
Integer.metaClass.toString = {
delegate == 42 ?
'The answer to life, the universe and everything' :
String.valueOf(delegate)
}
assert 42.toString() == 'The answer to life, the universe and everything'
assert 100.toString() == '100'
// Boolean
assert false.toBoolean() == false
Boolean.metaClass.toBoolean = { !delegate }
assert false.toBoolean() == true
Overriding methods using MetaClass
// Integer
assert '42' == 42.toString()
Integer.metaClass.toString = {
delegate == 42 ?
'The answer to life, the universe and everything' :
String.valueOf(delegate)
}
assert 42.toString() == 'The answer to life, the universe and everything'
assert 100.toString() == '100'
// Boolean
assert false.toBoolean() == false
Boolean.metaClass.toBoolean = { !delegate }
assert false.toBoolean() == true
Overriding methods using MetaClass
Categories
▷ MetaClass changes are “persistent”
▷ Change metaclass in confined code
▷ MOP modified only in the closure
Categories example
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
use (StringUtils) {
println "Lorem ipsum".truncate(5)
}
try {
println "Lorem ipsum".truncate(5)
} catch (MissingMethodException mme) {
println mme
}
// Execution
Lorem
groovy.lang.MissingMethodException: No
signature of method:
java.lang.String.truncate() is
applicable for argument types:
(java.lang.Integer) values: [5]
Possible solutions:
concat(java.lang.String), take(int)
Categories example
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
use (StringUtils) {
println "Lorem ipsum".truncate(5)
}
try {
println "Lorem ipsum".truncate(5)
} catch (MissingMethodException mme) {
println mme
}
// Execution
Lorem
groovy.lang.MissingMethodException: No
signature of method:
java.lang.String.truncate() is
applicable for argument types:
(java.lang.Integer) values: [5]
Possible solutions:
concat(java.lang.String), take(int)
Categories example
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
use (StringUtils) {
println "Lorem ipsum".truncate(5)
}
try {
println "Lorem ipsum".truncate(5)
} catch (MissingMethodException mme) {
println mme
}
// Execution
Lorem
groovy.lang.MissingMethodException: No
signature of method:
java.lang.String.truncate() is
applicable for argument types:
(java.lang.Integer) values: [5]
Possible solutions:
concat(java.lang.String), take(int)
Categories example
class StringUtils {
static String truncate(String text, Integer length, Boolean overflow = false) {
text.take(length) + (overflow ? '...' : '')
}
}
use (StringUtils) {
println "Lorem ipsum".truncate(5)
}
try {
println "Lorem ipsum".truncate(5)
} catch (MissingMethodException mme) {
println mme
}
// Execution
Lorem
groovy.lang.MissingMethodException: No
signature of method:
java.lang.String.truncate() is
applicable for argument types:
(java.lang.Integer) values: [5]
Possible solutions:
concat(java.lang.String), take(int)
Categories example (II)
import groovy.time.TimeCategory
use (TimeCategory) {
println (20.hours + 10.days.from.now)
// Fri Jul 17 20:00:00 CEST 2015
}
println TimeCategory.getHours(20).plus(TimeCategory.getDays(10).from.now)
// Fri Jul 17 20:00:00 CEST 2015
Categories example (II)
import groovy.time.TimeCategory
use (TimeCategory) {
println (20.hours + 10.days.from.now)
// Fri Jul 17 20:00:00 CEST 2015
}
println TimeCategory.getHours(20).plus(TimeCategory.getDays(10).from.now)
// Fri Jul 17 20:00:00 CEST 2015
Extension modules
▷ JAR file that provides extra methods
▷ Meta-information file
▷ Put jar in classpath to enhance classes
// src/main/groovy/londonggug/StringUtilsExtension.groovy
package londonggug
class StringUtilsExtension {
static String truncate(String self, Integer length, Boolean overflow = false) {
self.take(length) + (overflow ? '...' : '')
}
}
// Execute with:
// gradle build
// groovy -cp build/libs/string-
extensions-1.0.jar
ExtensionExample1.groovy
assert "Lorem..." == "Lorem ipsum".
truncate(5, true)
# src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule
moduleName = string-utils-module
moduleVersion = 0.1
extensionClasses = londonggug.StringUtilsExtension
Extension modules example
package londonggug
import spock.lang.Specification
class StringUtilsExtensionSpec extends Specification {
void 'test trucate'() {
expect:
"Lorem" == "Lorem ipsum".truncate(5)
"Lorem..." == "Lorem ipsum".truncate(5, true)
}
}
Extension modules example
// src/main/groovy/londonggug/StringUtilsExtension.groovy
package londonggug
class StringUtilsExtension {
static String truncate(String self, Integer length, Boolean overflow = false) {
self.take(length) + (overflow ? '...' : '')
}
}
# src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule
moduleName = string-utils-module
moduleVersion = 0.1
extensionClasses = londonggug.StringUtilsExtension
// Execute with:
// gradle build
// groovy -cp build/libs/string-
extensions-1.0.jar
ExtensionExample1.groovy
assert "Lorem..." == "Lorem ipsum".
truncate(5, true)
package londonggug
import spock.lang.Specification
class StringUtilsExtensionSpec extends Specification {
void 'test trucate'() {
expect:
"Lorem" == "Lorem ipsum".truncate(5)
"Lorem..." == "Lorem ipsum".truncate(5, true)
}
}
Extension modules example
// src/main/groovy/londonggug/StringUtilsExtension.groovy
package londonggug
class StringUtilsExtension {
static String truncate(String self, Integer length, Boolean overflow = false) {
self.take(length) + (overflow ? '...' : '')
}
}
// Execute with:
// gradle build
// groovy -cp build/libs/string-
extensions-1.0.jar
ExtensionExample1.groovy
assert "Lorem..." == "Lorem ipsum".
truncate(5, true)
# src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule
moduleName = string-utils-module
moduleVersion = 0.1
extensionClasses = londonggug.StringUtilsExtension
package londonggug
import spock.lang.Specification
class StringUtilsExtensionSpec extends Specification {
void 'test trucate'() {
expect:
"Lorem" == "Lorem ipsum".truncate(5)
"Lorem..." == "Lorem ipsum".truncate(5, true)
}
}
Extension modules example
// src/main/groovy/londonggug/StringUtilsExtension.groovy
package londonggug
class StringUtilsExtension {
static String truncate(String self, Integer length, Boolean overflow = false) {
self.take(length) + (overflow ? '...' : '')
}
}
// Execute with:
// gradle build
// groovy -cp build/libs/string-
extensions-1.0.jar
ExtensionExample1.groovy
assert "Lorem..." == "Lorem ipsum".
truncate(5, true)
# src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule
moduleName = string-utils-module
moduleVersion = 0.1
extensionClasses = londonggug.StringUtilsExtension
package londonggug
import spock.lang.Specification
class StringUtilsExtensionSpec extends Specification {
void 'test trucate'() {
expect:
"Lorem" == "Lorem ipsum".truncate(5)
"Lorem..." == "Lorem ipsum".truncate(5, true)
}
}
// src/main/groovy/londonggug/StringUtilsExtension.groovy
package londonggug
class StringUtilsExtension {
static String truncate(String self, Integer length, Boolean overflow = false) {
self.take(length) + (overflow ? '...' : '')
}
}
package londonggug
import spock.lang.Specification
class StringUtilsExtensionSpec extends Specification {
void 'test trucate'() {
expect:
"Lorem" == "Lorem ipsum".truncate(5)
"Lorem..." == "Lorem ipsum".truncate(5, true)
}
}
// Execute with:
// gradle build
// groovy -cp build/libs/string-
extensions-1.0.jar
ExtensionExample1.groovy
assert "Lorem..." == "Lorem ipsum".
truncate(5, true)
Extension modules example
# src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule
moduleName = string-utils-module
moduleVersion = 0.1
extensionClasses = londonggug.StringUtilsExtension
Mixins
▷ “Bring in” or “mix in” implementations
from multiple classes
▷ Calls first routed to mixed-in class
▷ Last mixin wins
▷ Not easily un-done
class SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
Mixins example
@Mixin([SpidermanPower])
class Person {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert !(person instanceof SpidermanPower)
Person.mixin SupermanPower
assert person.fly() == "Flying..."
assert !(person instanceof SupermanPower)
class SupermanPower {
String fly() {
"Flying..."
}
}
@Mixin([SpidermanPower])
class Person {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert !(person instanceof SpidermanPower)
Person.mixin SupermanPower
assert person.fly() == "Flying..."
assert !(person instanceof SupermanPower)
class SupermanPower {
String fly() {
"Flying..."
}
}
class SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
Mixins example
@Mixin([SpidermanPower])
class Person {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert !(person instanceof SpidermanPower)
Person.mixin SupermanPower
assert person.fly() == "Flying..."
assert !(person instanceof SupermanPower)
class SupermanPower {
String fly() {
"Flying..."
}
}
class SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
Mixins example
@Mixin([SpidermanPower])
class Person {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert !(person instanceof SpidermanPower)
Person.mixin SupermanPower
assert person.fly() == "Flying..."
assert !(person instanceof SupermanPower)
class SupermanPower {
String fly() {
"Flying..."
}
}
class SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
Mixins example
@Mixin([SpidermanPower])
class Person {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert !(person instanceof SpidermanPower)
Person.mixin SupermanPower
assert person.fly() == "Flying..."
assert !(person instanceof SupermanPower)
class SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
Mixins example
class SupermanPower {
String fly() {
"Flying..."
}
}
@Mixin([SpidermanPower])
class Person {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert !(person instanceof SpidermanPower)
Person.mixin SupermanPower
assert person.fly() == "Flying..."
assert !(person instanceof SupermanPower)
class SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
Mixins example
class SupermanPower {
String fly() {
"Flying..."
}
}
“When we started fixing mixin bugs we didn't know
if they were a bug or a feature, so we removed
mixins and add traits.
- Jochen Theodorou
(Greach 2015 Opening Keynote)
Traits
▷ Groovy 2.3+
▷ Similar to Java 8 default methods
▷ Supported in JDK 6, 7 and 8
▷ Stateful
▷ Composition over inheritance
▷ Documentation
class Person implements SpidermanPower {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert person instanceof SpidermanPower
def person2 = person.withTraits SupermanPower
assert person2.fly() == "Flying..."
assert person2 instanceof SupermanPower
Traits example
trait SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
trait SupermanPower {
String fly() {
"Flying..."
}
}
class Person implements SpidermanPower {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert person instanceof SpidermanPower
def person2 = person.withTraits SupermanPower
assert person2.fly() == "Flying..."
assert person2 instanceof SupermanPower
Traits example
trait SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
trait SupermanPower {
String fly() {
"Flying..."
}
}
class Person implements SpidermanPower {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert person instanceof SpidermanPower
def person2 = person.withTraits SupermanPower
assert person2.fly() == "Flying..."
assert person2 instanceof SupermanPower
Traits example
trait SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
trait SupermanPower {
String fly() {
"Flying..."
}
}
class Person implements SpidermanPower {}
def person = new Person()
assert person.spiderSense() == "Using spider-sense..."
assert person instanceof SpidermanPower
def person2 = person.withTraits SupermanPower
assert person2.fly() == "Flying..."
assert person2 instanceof SupermanPower
Traits example
trait SpidermanPower {
String spiderSense() {
"Using spider-sense..."
}
}
trait SupermanPower {
String fly() {
"Flying..."
}
}
MOP method
synthesis
MOP Method Synthesis
▷ Dynamically figure out behaviour upon
invocation
▷ It may not exist until it's called/executed
▷ “Intercept, Cache, Invoke” pattern
def p = new Person(name: 'Iván', age: 34)
assert p.respondsTo('sayHi')
assert p.respondsTo('sayHiTo', String)
assert !p.respondsTo('goodbye')
assert p.hasProperty('name')
assert !p.hasProperty('country')
Check for methods and properties
class Person {
String name
Integer age
String sayHi() {
"Hi, my name is ${name} and I'm ${age}"
}
String sayHiTo(String name) {
"Hi ${name}, how are you?"
}
}
def p = new Person(name: 'Iván', age: 35)
assert p.respondsTo('sayHi')
assert p.respondsTo('sayHiTo', String)
assert !p.respondsTo('goodbye')
assert p.hasProperty('age')
assert !p.hasProperty('country')
Check for methods and properties
class Person {
String name
Integer age
String sayHi() {
"Hi, my name is ${name} and I'm ${age}"
}
String sayHiTo(String name) {
"Hi ${name}, how are you?"
}
}
Check for methods and properties
class Person {
String name
Integer age
String sayHi() {
"Hi, my name is ${name} and I'm ${age}"
}
String sayHiTo(String name) {
"Hi ${name}, how are you?"
}
}
def p = new Person(name: 'Iván', age: 35)
assert p.respondsTo('sayHi')
assert p.respondsTo('sayHiTo', String)
assert !p.respondsTo('goodbye')
assert p.hasProperty('age')
assert !p.hasProperty('country')
Check for methods and properties
class Person {
String name
Integer age
String sayHi() {
"Hi, my name is ${name} and I'm ${age}"
}
String sayHiTo(String name) {
"Hi ${name}, how are you?"
}
}
def p = new Person(name: 'Iván', age: 35)
assert p.respondsTo('sayHi')
assert p.respondsTo('sayHiTo', String)
assert !p.respondsTo('goodbye')
assert p.hasProperty('age')
assert !p.hasProperty('country')
MethodMissing example
▷ Requirements:
– Send notifications to users by different
channels
– +50 notifications
– Not all notifications by all channels
– Extensible and open to future
modifications
MethodMissing example
abstract class Channel {
void sendNewFollower(String username, String follower) { }
void sendNewMessage(String username, String msg) { }
...
}
class EmailChannel extends Channel {
void sendNewFollower(String username, String follower) {
println "Sending email notification to '${username}' for new follower '${follower}'"
}
void sendNewMessage(String username, String msg) {
println "Sending email notification to '${username}' for new message '${msg}'"
}
}
class MobilePushChannel extends Channel {
void sendNewFollower(String username, String follower) {
println "Sending mobile push notification to '${username}' for new follower '${follower}'"
}
}
MethodMissing example
abstract class Channel {
void sendNewFollower(String username, String follower) { }
void sendNewMessage(String username, String msg) { }
...
}
class EmailChannel extends Channel {
void sendNewFollower(String username, String follower) {
println "Sending email notification to '${username}' for new follower '${follower}'"
}
void sendNewMessage(String username, String msg) {
println "Sending email notification to '${username}' for new message '${msg}'"
}
}
class MobilePushChannel extends Channel {
void sendNewFollower(String username, String follower) {
println "Sending mobile push notification to '${username}' for new follower '${follower}'"
}
}
MethodMissing example
abstract class Channel {
void sendNewFollower(String username, String follower) { }
void sendNewMessage(String username, String msg) { }
...
}
class EmailChannel extends Channel {
void sendNewFollower(String username, String follower) {
println "Sending email notification to '${username}' for new follower '${follower}'"
}
void sendNewMessage(String username, String msg) {
println "Sending email notification to '${username}' for new message '${msg}'"
}
}
class MobilePushChannel extends Channel {
void sendNewFollower(String username, String follower) {
println "Sending mobile push notification to '${username}' for new follower '${follower}'"
}
}
MethodMissing example
abstract class Channel {
void sendNewFollower(String username, String follower) { }
void sendNewMessage(String username, String msg) { }
...
}
class EmailChannel extends Channel {
void sendNewFollower(String username, String follower) {
println "Sending email notification to '${username}' for new follower '${follower}'"
}
void sendNewMessage(String username, String msg) {
println "Sending email notification to '${username}' for new message '${msg}'"
}
}
class MobilePushChannel extends Channel {
void sendNewFollower(String username, String follower) {
println "Sending mobile push notification to '${username}' for new follower '${follower}'"
}
}
MethodMissing example
class NotificationService {
List channels = []
def methodMissing(String name, args) {
System.out.println "...methodMissing called for ${name} with args ${args}"
// Generate the implementation
def implementation = { Object[] methodArgs ->
channels.each { channel ->
def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs)
return metaMethod.invoke(channel, methodArgs)
}
}
// Cache the implementation in the metaClass
NotificationService instance = this
instance.metaClass."$name" = implementation
// Execute it!
implementation(args)
}
}
MethodMissing example
class NotificationService {
List channels = []
def methodMissing(String name, args) {
System.out.println "...methodMissing called for ${name} with args ${args}"
// Generate the implementation
def implementation = { Object[] methodArgs ->
channels.each { channel ->
def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs)
return metaMethod.invoke(channel, methodArgs)
}
}
// Cache the implementation in the metaClass
NotificationService instance = this
instance.metaClass."$name" = implementation
// Execute it!
implementation(args)
}
}
MethodMissing example
class NotificationService {
List channels = []
def methodMissing(String name, args) {
System.out.println "...methodMissing called for ${name} with args ${args}"
// Generate the implementation
def implementation = { Object[] methodArgs ->
channels.each { channel ->
def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs)
return metaMethod.invoke(channel, methodArgs)
}
}
// Cache the implementation in the metaClass
NotificationService instance = this
instance.metaClass."$name" = implementation
// Execute it!
implementation(args)
}
}
notificationService.sendNewFollower(...)
notificationService.sendNewMessage(...)
MethodMissing example
class NotificationService {
List channels = []
def methodMissing(String name, args) {
System.out.println "...methodMissing called for ${name} with args ${args}"
// Generate the implementation
def implementation = { Object[] methodArgs ->
channels.each { channel ->
def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs)
return metaMethod.invoke(channel, methodArgs)
}
}
// Cache the implementation in the metaClass
NotificationService instance = this
instance.metaClass."$name" = implementation
// Execute it!
implementation(args)
}
}
MethodMissing example
class NotificationService {
List channels = []
def methodMissing(String name, args) {
System.out.println "...methodMissing called for ${name} with args ${args}"
// Generate the implementation
def implementation = { Object[] methodArgs ->
channels.each { channel ->
def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs)
return metaMethod.invoke(channel, methodArgs)
}
}
// Cache the implementation in the metaClass
NotificationService instance = this
instance.metaClass."$name" = implementation
// Execute it!
implementation(args)
}
}
MethodMissing example
// Execution
...methodMissing called for sendNewFollower with args [John, Peter]
Sending email notification to 'John' for new follower 'Peter'
Sending mobile push notification to 'John' for new follower 'Peter'
Sending email notification to 'Mary' for new follower 'Steve'
Sending mobile push notification to 'Mary' for new follower 'Steve'
...methodMissing called for sendNewMessage with args [Iván, Hello!]
Sending email notification to 'Iván' for new message 'Hello!'
def notificationService = new NotificationService(
channels: [new EmailChannel(), new MobilePushChannel()]
)
assert !notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("John", "Peter")
assert notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("Mary", "Steve")
notificationService.sendNewMessage("Iván", "Hello!")
MethodMissing example
// Execution
...methodMissing called for sendNewFollower with args [John, Peter]
Sending email notification to 'John' for new follower 'Peter'
Sending mobile push notification to 'John' for new follower 'Peter'
Sending email notification to 'Mary' for new follower 'Steve'
Sending mobile push notification to 'Mary' for new follower 'Steve'
...methodMissing called for sendNewMessage with args [Iván, Hello!]
Sending email notification to 'Iván' for new message 'Hello!'
def notificationService = new NotificationService(
channels: [new EmailChannel(), new MobilePushChannel()]
)
assert !notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("John", "Peter")
assert notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("Mary", "Steve")
notificationService.sendNewMessage("Iván", "Hello!")
MethodMissing example
// Execution
...methodMissing called for sendNewFollower with args [John, Peter]
Sending email notification to 'John' for new follower 'Peter'
Sending mobile push notification to 'John' for new follower 'Peter'
Sending email notification to 'Mary' for new follower 'Steve'
Sending mobile push notification to 'Mary' for new follower 'Steve'
...methodMissing called for sendNewMessage with args [Iván, Hello!]
Sending email notification to 'Iván' for new message 'Hello!'
def notificationService = new NotificationService(
channels: [new EmailChannel(), new MobilePushChannel()]
)
assert !notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("John", "Peter")
assert notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("Mary", "Steve")
notificationService.sendNewMessage("Iván", "Hello!")
MethodMissing example
// Execution
...methodMissing called for sendNewFollower with args [John, Peter]
Sending email notification to 'John' for new follower 'Peter'
Sending mobile push notification to 'John' for new follower 'Peter'
Sending email notification to 'Mary' for new follower 'Steve'
Sending mobile push notification to 'Mary' for new follower 'Steve'
...methodMissing called for sendNewMessage with args [Iván, Hello!]
Sending email notification to 'Iván' for new message 'Hello!'
def notificationService = new NotificationService(
channels: [new EmailChannel(), new MobilePushChannel()]
)
assert !notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("John", "Peter")
assert notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("Mary", "Steve")
notificationService.sendNewMessage("Iván", "Hello!")
MethodMissing example
// Execution
...methodMissing called for sendNewFollower with args [John, Peter]
Sending email notification to 'John' for new follower 'Peter'
Sending mobile push notification to 'John' for new follower 'Peter'
Sending email notification to 'Mary' for new follower 'Steve'
Sending mobile push notification to 'Mary' for new follower 'Steve'
...methodMissing called for sendNewMessage with args [Iván, Hello!]
Sending email notification to 'Iván' for new message 'Hello!'
def notificationService = new NotificationService(
channels: [new EmailChannel(), new MobilePushChannel()]
)
assert !notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("John", "Peter")
assert notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("Mary", "Steve")
notificationService.sendNewMessage("Iván", "Hello!")class EmailChannel extends Channel {
void sendNewFollower(String username, String follower) {…}
void sendNewMessage(String username, String msg) {…}
}
class MobilePushChannel extends Channel {
void sendNewFollower(String username, String follower) {…}
}
MethodMissing example
// Execution
...methodMissing called for sendNewFollower with args [John, Peter]
Sending email notification to 'John' for new follower 'Peter'
Sending mobile push notification to 'John' for new follower 'Peter'
Sending email notification to 'Mary' for new follower 'Steve'
Sending mobile push notification to 'Mary' for new follower 'Steve'
...methodMissing called for sendNewMessage with args [Iván, Hello!]
Sending email notification to 'Iván' for new message 'Hello!'
def notificationService = new NotificationService(
channels: [new EmailChannel(), new MobilePushChannel()]
)
assert !notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("John", "Peter")
assert notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("Mary", "Steve")
notificationService.sendNewMessage("Iván", "Hello!")
MethodMissing example
// Execution
...methodMissing called for sendNewFollower with args [John, Peter]
Sending email notification to 'John' for new follower 'Peter'
Sending mobile push notification to 'John' for new follower 'Peter'
Sending email notification to 'Mary' for new follower 'Steve'
Sending mobile push notification to 'Mary' for new follower 'Steve'
...methodMissing called for sendNewMessage with args [Iván, Hello!]
Sending email notification to 'Iván' for new message 'Hello!'
def notificationService = new NotificationService(
channels: [new EmailChannel(), new MobilePushChannel()]
)
assert !notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("John", "Peter")
assert notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("Mary", "Steve")
notificationService.sendNewMessage("Iván", "Hello!")
MethodMissing example
def notificationService = new NotificationService(
channels: [new EmailChannel(), new MobilePushChannel()]
)
assert !notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("John", "Peter")
assert notificationService.respondsTo('sendNewFollower', String, String)
notificationService.sendNewFollower("Mary", "Steve")
notificationService.sendNewMessage("Iván", "Hello!")
// Execution
...methodMissing called for sendNewFollower with args [John, Peter]
Sending email notification to 'John' for new follower 'Peter'
Sending mobile push notification to 'John' for new follower 'Peter'
Sending email notification to 'Mary' for new follower 'Steve'
Sending mobile push notification to 'Mary' for new follower 'Steve'
...methodMissing called for sendNewMessage with args [Iván, Hello!]
Sending email notification to 'Iván' for new message 'Hello!'
2.
Why we should use
metaprogramming?
Let’s review some concepts
Metaprogramming
out-of-the box
Easy and very
powerful
Write better code
Add behaviour
easily
Take advantage of
this power
Because Groovy,
it's groovy
With great power
comes great
responsibility
Thanks!
Any questions?
@ilopmar
lopez.ivan@gmail.com
https://github.com/lmivan
Iván López

More Related Content

Similar to London-GGUG 2015 - Metaprogramming Options with Groovy

The Ring programming language version 1.7 book - Part 40 of 196
The Ring programming language version 1.7 book - Part 40 of 196The Ring programming language version 1.7 book - Part 40 of 196
The Ring programming language version 1.7 book - Part 40 of 196
Mahmoud Samir Fayed
 
Reflection
ReflectionReflection
Reflection
Tony Nguyen
 
Reflection
ReflectionReflection
Reflection
Young Alista
 
Reflection
ReflectionReflection
Reflection
Harry Potter
 
Reflection
ReflectionReflection
Reflection
Fraboni Ec
 
Reflection
ReflectionReflection
Reflection
James Wong
 
Reflection
ReflectionReflection
Reflection
Luis Goldster
 
openFrameworks 007 - utils
openFrameworks 007 - utilsopenFrameworks 007 - utils
openFrameworks 007 - utils
roxlu
 
Lec 8 03_sept [compatibility mode]
Lec 8 03_sept [compatibility mode]Lec 8 03_sept [compatibility mode]
Lec 8 03_sept [compatibility mode]
Palak Sanghani
 
The Ring programming language version 1.2 book - Part 25 of 84
The Ring programming language version 1.2 book - Part 25 of 84The Ring programming language version 1.2 book - Part 25 of 84
The Ring programming language version 1.2 book - Part 25 of 84
Mahmoud Samir Fayed
 
The Ring programming language version 1.5.3 book - Part 36 of 184
The Ring programming language version 1.5.3 book - Part 36 of 184The Ring programming language version 1.5.3 book - Part 36 of 184
The Ring programming language version 1.5.3 book - Part 36 of 184
Mahmoud Samir Fayed
 
Introduction to Java Strings, By Kavita Ganesan
Introduction to Java Strings, By Kavita GanesanIntroduction to Java Strings, By Kavita Ganesan
Introduction to Java Strings, By Kavita Ganesan
Kavita Ganesan
 
Deep dumpster diving 2010
Deep dumpster diving 2010Deep dumpster diving 2010
Deep dumpster diving 2010
RonnBlack
 
Chapter 2
Chapter 2Chapter 2
Rust concurrency tutorial 2015 12-02
Rust concurrency tutorial 2015 12-02Rust concurrency tutorial 2015 12-02
Rust concurrency tutorial 2015 12-02
nikomatsakis
 
2013 DevFest Vienna - Bad Tests, Good Tests
2013 DevFest Vienna - Bad Tests, Good Tests2013 DevFest Vienna - Bad Tests, Good Tests
2013 DevFest Vienna - Bad Tests, Good Tests
Tomek Kaczanowski
 
The Ring programming language version 1.6 book - Part 39 of 189
The Ring programming language version 1.6 book - Part 39 of 189The Ring programming language version 1.6 book - Part 39 of 189
The Ring programming language version 1.6 book - Part 39 of 189
Mahmoud Samir Fayed
 
Java for the Impatient, Java Constructors, Scope, Wrappers, Inheritance, and ...
Java for the Impatient, Java Constructors, Scope, Wrappers, Inheritance, and ...Java for the Impatient, Java Constructors, Scope, Wrappers, Inheritance, and ...
Java for the Impatient, Java Constructors, Scope, Wrappers, Inheritance, and ...
argsstring
 
The Ring programming language version 1.3 book - Part 27 of 88
The Ring programming language version 1.3 book - Part 27 of 88The Ring programming language version 1.3 book - Part 27 of 88
The Ring programming language version 1.3 book - Part 27 of 88
Mahmoud Samir Fayed
 
Core java oop
Core java oopCore java oop
Core java oop
Parth Shah
 

Similar to London-GGUG 2015 - Metaprogramming Options with Groovy (20)

The Ring programming language version 1.7 book - Part 40 of 196
The Ring programming language version 1.7 book - Part 40 of 196The Ring programming language version 1.7 book - Part 40 of 196
The Ring programming language version 1.7 book - Part 40 of 196
 
Reflection
ReflectionReflection
Reflection
 
Reflection
ReflectionReflection
Reflection
 
Reflection
ReflectionReflection
Reflection
 
Reflection
ReflectionReflection
Reflection
 
Reflection
ReflectionReflection
Reflection
 
Reflection
ReflectionReflection
Reflection
 
openFrameworks 007 - utils
openFrameworks 007 - utilsopenFrameworks 007 - utils
openFrameworks 007 - utils
 
Lec 8 03_sept [compatibility mode]
Lec 8 03_sept [compatibility mode]Lec 8 03_sept [compatibility mode]
Lec 8 03_sept [compatibility mode]
 
The Ring programming language version 1.2 book - Part 25 of 84
The Ring programming language version 1.2 book - Part 25 of 84The Ring programming language version 1.2 book - Part 25 of 84
The Ring programming language version 1.2 book - Part 25 of 84
 
The Ring programming language version 1.5.3 book - Part 36 of 184
The Ring programming language version 1.5.3 book - Part 36 of 184The Ring programming language version 1.5.3 book - Part 36 of 184
The Ring programming language version 1.5.3 book - Part 36 of 184
 
Introduction to Java Strings, By Kavita Ganesan
Introduction to Java Strings, By Kavita GanesanIntroduction to Java Strings, By Kavita Ganesan
Introduction to Java Strings, By Kavita Ganesan
 
Deep dumpster diving 2010
Deep dumpster diving 2010Deep dumpster diving 2010
Deep dumpster diving 2010
 
Chapter 2
Chapter 2Chapter 2
Chapter 2
 
Rust concurrency tutorial 2015 12-02
Rust concurrency tutorial 2015 12-02Rust concurrency tutorial 2015 12-02
Rust concurrency tutorial 2015 12-02
 
2013 DevFest Vienna - Bad Tests, Good Tests
2013 DevFest Vienna - Bad Tests, Good Tests2013 DevFest Vienna - Bad Tests, Good Tests
2013 DevFest Vienna - Bad Tests, Good Tests
 
The Ring programming language version 1.6 book - Part 39 of 189
The Ring programming language version 1.6 book - Part 39 of 189The Ring programming language version 1.6 book - Part 39 of 189
The Ring programming language version 1.6 book - Part 39 of 189
 
Java for the Impatient, Java Constructors, Scope, Wrappers, Inheritance, and ...
Java for the Impatient, Java Constructors, Scope, Wrappers, Inheritance, and ...Java for the Impatient, Java Constructors, Scope, Wrappers, Inheritance, and ...
Java for the Impatient, Java Constructors, Scope, Wrappers, Inheritance, and ...
 
The Ring programming language version 1.3 book - Part 27 of 88
The Ring programming language version 1.3 book - Part 27 of 88The Ring programming language version 1.3 book - Part 27 of 88
The Ring programming language version 1.3 book - Part 27 of 88
 
Core java oop
Core java oopCore java oop
Core java oop
 

More from Iván López Martín

SalmorejoTech 2024 - Spring Boot <3 Testcontainers
SalmorejoTech 2024 - Spring Boot <3 TestcontainersSalmorejoTech 2024 - Spring Boot <3 Testcontainers
SalmorejoTech 2024 - Spring Boot <3 Testcontainers
Iván López Martín
 
CommitConf 2024 - Spring Boot <3 Testcontainers
CommitConf 2024 - Spring Boot <3 TestcontainersCommitConf 2024 - Spring Boot <3 Testcontainers
CommitConf 2024 - Spring Boot <3 Testcontainers
Iván López Martín
 
Voxxed Days CERN 2024 - Spring Boot <3 Testcontainers.pdf
Voxxed Days CERN 2024 - Spring Boot <3 Testcontainers.pdfVoxxed Days CERN 2024 - Spring Boot <3 Testcontainers.pdf
Voxxed Days CERN 2024 - Spring Boot <3 Testcontainers.pdf
Iván López Martín
 
VMware - Testcontainers y Spring Boot
VMware - Testcontainers y Spring BootVMware - Testcontainers y Spring Boot
VMware - Testcontainers y Spring Boot
Iván López Martín
 
Spring IO 2023 - Dynamic OpenAPIs with Spring Cloud Gateway
Spring IO 2023 - Dynamic OpenAPIs with Spring Cloud GatewaySpring IO 2023 - Dynamic OpenAPIs with Spring Cloud Gateway
Spring IO 2023 - Dynamic OpenAPIs with Spring Cloud Gateway
Iván López Martín
 
Codemotion Madrid 2023 - Testcontainers y Spring Boot
Codemotion Madrid 2023 - Testcontainers y Spring BootCodemotion Madrid 2023 - Testcontainers y Spring Boot
Codemotion Madrid 2023 - Testcontainers y Spring Boot
Iván López Martín
 
CommitConf 2023 - Spring Framework 6 y Spring Boot 3
CommitConf 2023 - Spring Framework 6 y Spring Boot 3CommitConf 2023 - Spring Framework 6 y Spring Boot 3
CommitConf 2023 - Spring Framework 6 y Spring Boot 3
Iván López Martín
 
Construyendo un API REST con Spring Boot y GraalVM
Construyendo un API REST con Spring Boot y GraalVMConstruyendo un API REST con Spring Boot y GraalVM
Construyendo un API REST con Spring Boot y GraalVM
Iván López Martín
 
jLove 2020 - Micronaut and graalvm: The power of AoT
jLove 2020 - Micronaut and graalvm: The power of AoTjLove 2020 - Micronaut and graalvm: The power of AoT
jLove 2020 - Micronaut and graalvm: The power of AoT
Iván López Martín
 
Codemotion Madrid 2020 - Serverless con Micronaut
Codemotion Madrid 2020 - Serverless con MicronautCodemotion Madrid 2020 - Serverless con Micronaut
Codemotion Madrid 2020 - Serverless con Micronaut
Iván López Martín
 
JConf Perú 2020 - ¡Micronaut en acción!
JConf Perú 2020 - ¡Micronaut en acción!JConf Perú 2020 - ¡Micronaut en acción!
JConf Perú 2020 - ¡Micronaut en acción!
Iván López Martín
 
JConf Perú 2020 - Micronaut + GraalVM = <3
JConf Perú 2020 - Micronaut + GraalVM = <3JConf Perú 2020 - Micronaut + GraalVM = <3
JConf Perú 2020 - Micronaut + GraalVM = <3
Iván López Martín
 
JConf México 2020 - Micronaut + GraalVM = <3
JConf México 2020 - Micronaut + GraalVM = <3JConf México 2020 - Micronaut + GraalVM = <3
JConf México 2020 - Micronaut + GraalVM = <3
Iván López Martín
 
Developing Micronaut Applications With IntelliJ IDEA
Developing Micronaut Applications With IntelliJ IDEADeveloping Micronaut Applications With IntelliJ IDEA
Developing Micronaut Applications With IntelliJ IDEA
Iván López Martín
 
CommitConf 2019 - Micronaut y GraalVm: La combinación perfecta
CommitConf 2019 - Micronaut y GraalVm: La combinación perfectaCommitConf 2019 - Micronaut y GraalVm: La combinación perfecta
CommitConf 2019 - Micronaut y GraalVm: La combinación perfecta
Iván López Martín
 
Codemotion Madrid 2019 - ¡GraalVM y Micronaut: compañeros perfectos!
Codemotion Madrid 2019 - ¡GraalVM y Micronaut: compañeros perfectos!Codemotion Madrid 2019 - ¡GraalVM y Micronaut: compañeros perfectos!
Codemotion Madrid 2019 - ¡GraalVM y Micronaut: compañeros perfectos!
Iván López Martín
 
Greach 2019 - Creating Micronaut Configurations
Greach 2019 - Creating Micronaut ConfigurationsGreach 2019 - Creating Micronaut Configurations
Greach 2019 - Creating Micronaut Configurations
Iván López Martín
 
VoxxedDays Bucharest 2019 - Alexa, nice to meet you
VoxxedDays Bucharest 2019 - Alexa, nice to meet youVoxxedDays Bucharest 2019 - Alexa, nice to meet you
VoxxedDays Bucharest 2019 - Alexa, nice to meet you
Iván López Martín
 
JavaDay Lviv 2019 - Micronaut in action!
JavaDay Lviv 2019 - Micronaut in action!JavaDay Lviv 2019 - Micronaut in action!
JavaDay Lviv 2019 - Micronaut in action!
Iván López Martín
 
CrossDvlup Madrid 2019 - Alexa, encantado de conocerte
CrossDvlup Madrid 2019 - Alexa, encantado de conocerteCrossDvlup Madrid 2019 - Alexa, encantado de conocerte
CrossDvlup Madrid 2019 - Alexa, encantado de conocerte
Iván López Martín
 

More from Iván López Martín (20)

SalmorejoTech 2024 - Spring Boot <3 Testcontainers
SalmorejoTech 2024 - Spring Boot <3 TestcontainersSalmorejoTech 2024 - Spring Boot <3 Testcontainers
SalmorejoTech 2024 - Spring Boot <3 Testcontainers
 
CommitConf 2024 - Spring Boot <3 Testcontainers
CommitConf 2024 - Spring Boot <3 TestcontainersCommitConf 2024 - Spring Boot <3 Testcontainers
CommitConf 2024 - Spring Boot <3 Testcontainers
 
Voxxed Days CERN 2024 - Spring Boot <3 Testcontainers.pdf
Voxxed Days CERN 2024 - Spring Boot <3 Testcontainers.pdfVoxxed Days CERN 2024 - Spring Boot <3 Testcontainers.pdf
Voxxed Days CERN 2024 - Spring Boot <3 Testcontainers.pdf
 
VMware - Testcontainers y Spring Boot
VMware - Testcontainers y Spring BootVMware - Testcontainers y Spring Boot
VMware - Testcontainers y Spring Boot
 
Spring IO 2023 - Dynamic OpenAPIs with Spring Cloud Gateway
Spring IO 2023 - Dynamic OpenAPIs with Spring Cloud GatewaySpring IO 2023 - Dynamic OpenAPIs with Spring Cloud Gateway
Spring IO 2023 - Dynamic OpenAPIs with Spring Cloud Gateway
 
Codemotion Madrid 2023 - Testcontainers y Spring Boot
Codemotion Madrid 2023 - Testcontainers y Spring BootCodemotion Madrid 2023 - Testcontainers y Spring Boot
Codemotion Madrid 2023 - Testcontainers y Spring Boot
 
CommitConf 2023 - Spring Framework 6 y Spring Boot 3
CommitConf 2023 - Spring Framework 6 y Spring Boot 3CommitConf 2023 - Spring Framework 6 y Spring Boot 3
CommitConf 2023 - Spring Framework 6 y Spring Boot 3
 
Construyendo un API REST con Spring Boot y GraalVM
Construyendo un API REST con Spring Boot y GraalVMConstruyendo un API REST con Spring Boot y GraalVM
Construyendo un API REST con Spring Boot y GraalVM
 
jLove 2020 - Micronaut and graalvm: The power of AoT
jLove 2020 - Micronaut and graalvm: The power of AoTjLove 2020 - Micronaut and graalvm: The power of AoT
jLove 2020 - Micronaut and graalvm: The power of AoT
 
Codemotion Madrid 2020 - Serverless con Micronaut
Codemotion Madrid 2020 - Serverless con MicronautCodemotion Madrid 2020 - Serverless con Micronaut
Codemotion Madrid 2020 - Serverless con Micronaut
 
JConf Perú 2020 - ¡Micronaut en acción!
JConf Perú 2020 - ¡Micronaut en acción!JConf Perú 2020 - ¡Micronaut en acción!
JConf Perú 2020 - ¡Micronaut en acción!
 
JConf Perú 2020 - Micronaut + GraalVM = <3
JConf Perú 2020 - Micronaut + GraalVM = <3JConf Perú 2020 - Micronaut + GraalVM = <3
JConf Perú 2020 - Micronaut + GraalVM = <3
 
JConf México 2020 - Micronaut + GraalVM = <3
JConf México 2020 - Micronaut + GraalVM = <3JConf México 2020 - Micronaut + GraalVM = <3
JConf México 2020 - Micronaut + GraalVM = <3
 
Developing Micronaut Applications With IntelliJ IDEA
Developing Micronaut Applications With IntelliJ IDEADeveloping Micronaut Applications With IntelliJ IDEA
Developing Micronaut Applications With IntelliJ IDEA
 
CommitConf 2019 - Micronaut y GraalVm: La combinación perfecta
CommitConf 2019 - Micronaut y GraalVm: La combinación perfectaCommitConf 2019 - Micronaut y GraalVm: La combinación perfecta
CommitConf 2019 - Micronaut y GraalVm: La combinación perfecta
 
Codemotion Madrid 2019 - ¡GraalVM y Micronaut: compañeros perfectos!
Codemotion Madrid 2019 - ¡GraalVM y Micronaut: compañeros perfectos!Codemotion Madrid 2019 - ¡GraalVM y Micronaut: compañeros perfectos!
Codemotion Madrid 2019 - ¡GraalVM y Micronaut: compañeros perfectos!
 
Greach 2019 - Creating Micronaut Configurations
Greach 2019 - Creating Micronaut ConfigurationsGreach 2019 - Creating Micronaut Configurations
Greach 2019 - Creating Micronaut Configurations
 
VoxxedDays Bucharest 2019 - Alexa, nice to meet you
VoxxedDays Bucharest 2019 - Alexa, nice to meet youVoxxedDays Bucharest 2019 - Alexa, nice to meet you
VoxxedDays Bucharest 2019 - Alexa, nice to meet you
 
JavaDay Lviv 2019 - Micronaut in action!
JavaDay Lviv 2019 - Micronaut in action!JavaDay Lviv 2019 - Micronaut in action!
JavaDay Lviv 2019 - Micronaut in action!
 
CrossDvlup Madrid 2019 - Alexa, encantado de conocerte
CrossDvlup Madrid 2019 - Alexa, encantado de conocerteCrossDvlup Madrid 2019 - Alexa, encantado de conocerte
CrossDvlup Madrid 2019 - Alexa, encantado de conocerte
 

Recently uploaded

BLOCKCHAIN FOR DUMMIES: GUIDEBOOK FOR ALL
BLOCKCHAIN FOR DUMMIES: GUIDEBOOK FOR ALLBLOCKCHAIN FOR DUMMIES: GUIDEBOOK FOR ALL
BLOCKCHAIN FOR DUMMIES: GUIDEBOOK FOR ALL
Liveplex
 
WhatsApp Image 2024-03-27 at 08.19.52_bfd93109.pdf
WhatsApp Image 2024-03-27 at 08.19.52_bfd93109.pdfWhatsApp Image 2024-03-27 at 08.19.52_bfd93109.pdf
WhatsApp Image 2024-03-27 at 08.19.52_bfd93109.pdf
ArgaBisma
 
IPLOOK Remote-Sensing Satellite Solution
IPLOOK Remote-Sensing Satellite SolutionIPLOOK Remote-Sensing Satellite Solution
IPLOOK Remote-Sensing Satellite Solution
IPLOOK Networks
 
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-InTrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc
 
Implementations of Fused Deposition Modeling in real world
Implementations of Fused Deposition Modeling  in real worldImplementations of Fused Deposition Modeling  in real world
Implementations of Fused Deposition Modeling in real world
Emerging Tech
 
Advanced Techniques for Cyber Security Analysis and Anomaly Detection
Advanced Techniques for Cyber Security Analysis and Anomaly DetectionAdvanced Techniques for Cyber Security Analysis and Anomaly Detection
Advanced Techniques for Cyber Security Analysis and Anomaly Detection
Bert Blevins
 
find out more about the role of autonomous vehicles in facing global challenges
find out more about the role of autonomous vehicles in facing global challengesfind out more about the role of autonomous vehicles in facing global challenges
find out more about the role of autonomous vehicles in facing global challenges
huseindihon
 
Salesforce AI & Einstein Copilot Workshop
Salesforce AI & Einstein Copilot WorkshopSalesforce AI & Einstein Copilot Workshop
Salesforce AI & Einstein Copilot Workshop
CEPTES Software Inc
 
“Deploying Large Language Models on a Raspberry Pi,” a Presentation from Usef...
“Deploying Large Language Models on a Raspberry Pi,” a Presentation from Usef...“Deploying Large Language Models on a Raspberry Pi,” a Presentation from Usef...
“Deploying Large Language Models on a Raspberry Pi,” a Presentation from Usef...
Edge AI and Vision Alliance
 
How RPA Help in the Transportation and Logistics Industry.pptx
How RPA Help in the Transportation and Logistics Industry.pptxHow RPA Help in the Transportation and Logistics Industry.pptx
How RPA Help in the Transportation and Logistics Industry.pptx
SynapseIndia
 
RPA In Healthcare Benefits, Use Case, Trend And Challenges 2024.pptx
RPA In Healthcare Benefits, Use Case, Trend And Challenges 2024.pptxRPA In Healthcare Benefits, Use Case, Trend And Challenges 2024.pptx
RPA In Healthcare Benefits, Use Case, Trend And Challenges 2024.pptx
SynapseIndia
 
Evolution of iPaaS - simplify IT workloads to provide a unified view of data...
Evolution of iPaaS - simplify IT workloads to provide a unified view of  data...Evolution of iPaaS - simplify IT workloads to provide a unified view of  data...
Evolution of iPaaS - simplify IT workloads to provide a unified view of data...
Torry Harris
 
Scaling Connections in PostgreSQL Postgres Bangalore(PGBLR) Meetup-2 - Mydbops
Scaling Connections in PostgreSQL Postgres Bangalore(PGBLR) Meetup-2 - MydbopsScaling Connections in PostgreSQL Postgres Bangalore(PGBLR) Meetup-2 - Mydbops
Scaling Connections in PostgreSQL Postgres Bangalore(PGBLR) Meetup-2 - Mydbops
Mydbops
 
Pigging Solutions Sustainability brochure.pdf
Pigging Solutions Sustainability brochure.pdfPigging Solutions Sustainability brochure.pdf
Pigging Solutions Sustainability brochure.pdf
Pigging Solutions
 
ScrumGathering New Orleans 2024 Catherine Louis.pdf
ScrumGathering New Orleans 2024  Catherine Louis.pdfScrumGathering New Orleans 2024  Catherine Louis.pdf
ScrumGathering New Orleans 2024 Catherine Louis.pdf
Global Agile Consulting- CLL-Group, LLC
 
Understanding Insider Security Threats: Types, Examples, Effects, and Mitigat...
Understanding Insider Security Threats: Types, Examples, Effects, and Mitigat...Understanding Insider Security Threats: Types, Examples, Effects, and Mitigat...
Understanding Insider Security Threats: Types, Examples, Effects, and Mitigat...
Bert Blevins
 
DealBook of Ukraine: 2024 edition
DealBook of Ukraine: 2024 editionDealBook of Ukraine: 2024 edition
DealBook of Ukraine: 2024 edition
Yevgen Sysoyev
 
Data Integration Basics: Merging & Joining Data
Data Integration Basics: Merging & Joining DataData Integration Basics: Merging & Joining Data
Data Integration Basics: Merging & Joining Data
Safe Software
 
Overview of Enterprise-scale landing zones using Cloud Adoption Framework Rea...
Overview of Enterprise-scale landing zones using Cloud Adoption Framework Rea...Overview of Enterprise-scale landing zones using Cloud Adoption Framework Rea...
Overview of Enterprise-scale landing zones using Cloud Adoption Framework Rea...
MarceloMiranda38200
 
The Role of Technology in Payroll Statutory Compliance (1).pdf
The Role of Technology in Payroll Statutory Compliance (1).pdfThe Role of Technology in Payroll Statutory Compliance (1).pdf
The Role of Technology in Payroll Statutory Compliance (1).pdf
paysquare consultancy
 

Recently uploaded (20)

BLOCKCHAIN FOR DUMMIES: GUIDEBOOK FOR ALL
BLOCKCHAIN FOR DUMMIES: GUIDEBOOK FOR ALLBLOCKCHAIN FOR DUMMIES: GUIDEBOOK FOR ALL
BLOCKCHAIN FOR DUMMIES: GUIDEBOOK FOR ALL
 
WhatsApp Image 2024-03-27 at 08.19.52_bfd93109.pdf
WhatsApp Image 2024-03-27 at 08.19.52_bfd93109.pdfWhatsApp Image 2024-03-27 at 08.19.52_bfd93109.pdf
WhatsApp Image 2024-03-27 at 08.19.52_bfd93109.pdf
 
IPLOOK Remote-Sensing Satellite Solution
IPLOOK Remote-Sensing Satellite SolutionIPLOOK Remote-Sensing Satellite Solution
IPLOOK Remote-Sensing Satellite Solution
 
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-InTrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
 
Implementations of Fused Deposition Modeling in real world
Implementations of Fused Deposition Modeling  in real worldImplementations of Fused Deposition Modeling  in real world
Implementations of Fused Deposition Modeling in real world
 
Advanced Techniques for Cyber Security Analysis and Anomaly Detection
Advanced Techniques for Cyber Security Analysis and Anomaly DetectionAdvanced Techniques for Cyber Security Analysis and Anomaly Detection
Advanced Techniques for Cyber Security Analysis and Anomaly Detection
 
find out more about the role of autonomous vehicles in facing global challenges
find out more about the role of autonomous vehicles in facing global challengesfind out more about the role of autonomous vehicles in facing global challenges
find out more about the role of autonomous vehicles in facing global challenges
 
Salesforce AI & Einstein Copilot Workshop
Salesforce AI & Einstein Copilot WorkshopSalesforce AI & Einstein Copilot Workshop
Salesforce AI & Einstein Copilot Workshop
 
“Deploying Large Language Models on a Raspberry Pi,” a Presentation from Usef...
“Deploying Large Language Models on a Raspberry Pi,” a Presentation from Usef...“Deploying Large Language Models on a Raspberry Pi,” a Presentation from Usef...
“Deploying Large Language Models on a Raspberry Pi,” a Presentation from Usef...
 
How RPA Help in the Transportation and Logistics Industry.pptx
How RPA Help in the Transportation and Logistics Industry.pptxHow RPA Help in the Transportation and Logistics Industry.pptx
How RPA Help in the Transportation and Logistics Industry.pptx
 
RPA In Healthcare Benefits, Use Case, Trend And Challenges 2024.pptx
RPA In Healthcare Benefits, Use Case, Trend And Challenges 2024.pptxRPA In Healthcare Benefits, Use Case, Trend And Challenges 2024.pptx
RPA In Healthcare Benefits, Use Case, Trend And Challenges 2024.pptx
 
Evolution of iPaaS - simplify IT workloads to provide a unified view of data...
Evolution of iPaaS - simplify IT workloads to provide a unified view of  data...Evolution of iPaaS - simplify IT workloads to provide a unified view of  data...
Evolution of iPaaS - simplify IT workloads to provide a unified view of data...
 
Scaling Connections in PostgreSQL Postgres Bangalore(PGBLR) Meetup-2 - Mydbops
Scaling Connections in PostgreSQL Postgres Bangalore(PGBLR) Meetup-2 - MydbopsScaling Connections in PostgreSQL Postgres Bangalore(PGBLR) Meetup-2 - Mydbops
Scaling Connections in PostgreSQL Postgres Bangalore(PGBLR) Meetup-2 - Mydbops
 
Pigging Solutions Sustainability brochure.pdf
Pigging Solutions Sustainability brochure.pdfPigging Solutions Sustainability brochure.pdf
Pigging Solutions Sustainability brochure.pdf
 
ScrumGathering New Orleans 2024 Catherine Louis.pdf
ScrumGathering New Orleans 2024  Catherine Louis.pdfScrumGathering New Orleans 2024  Catherine Louis.pdf
ScrumGathering New Orleans 2024 Catherine Louis.pdf
 
Understanding Insider Security Threats: Types, Examples, Effects, and Mitigat...
Understanding Insider Security Threats: Types, Examples, Effects, and Mitigat...Understanding Insider Security Threats: Types, Examples, Effects, and Mitigat...
Understanding Insider Security Threats: Types, Examples, Effects, and Mitigat...
 
DealBook of Ukraine: 2024 edition
DealBook of Ukraine: 2024 editionDealBook of Ukraine: 2024 edition
DealBook of Ukraine: 2024 edition
 
Data Integration Basics: Merging & Joining Data
Data Integration Basics: Merging & Joining DataData Integration Basics: Merging & Joining Data
Data Integration Basics: Merging & Joining Data
 
Overview of Enterprise-scale landing zones using Cloud Adoption Framework Rea...
Overview of Enterprise-scale landing zones using Cloud Adoption Framework Rea...Overview of Enterprise-scale landing zones using Cloud Adoption Framework Rea...
Overview of Enterprise-scale landing zones using Cloud Adoption Framework Rea...
 
The Role of Technology in Payroll Statutory Compliance (1).pdf
The Role of Technology in Payroll Statutory Compliance (1).pdfThe Role of Technology in Payroll Statutory Compliance (1).pdf
The Role of Technology in Payroll Statutory Compliance (1).pdf
 

London-GGUG 2015 - Metaprogramming Options with Groovy

  • 1. METAPROGRAMMING OPTIONS WITH GROOVY METAPROGRAMMING OPTIONS WITH GROOVY Iván López @ilopmarIván López @ilopmar@LondonGGUG@LondonGGUG
  • 2. Hello! I am Iván López @ilopmar http://greachconf.com@madridgug
  • 3. ▷ 1st rule: You DO talk about the London-GGUG ▷ 2nd rule: If it's your first London- GGUG you HAVE to talk ▷3rd rule: You have to be awesome (by David Dawson) London-GGUG rules
  • 4. Groovy is dynamic ▷ “Delay” to runtime some decisions ▷ Add properties/behaviours in runtime ▷ Wide range of applicability
  • 6. “Metaprogramming is the writing of computer programs that write or manipulate other programs (or themselves) as their data. - Wikipedia
  • 8. Runtime metaprogramming ▷ Groovy provides this through Meta- Object Protocol (MOP) ▷ Use MOP to: – Invoke methods dynamically – Synthesize classes and methods on the fly
  • 9. What is the Meta Object Protocol? Groovy Groovy Java Java MOP
  • 10. MetaClass ▷ MetaClass registry for each class ▷ Collection of methods/properties ▷ We can always modify the metaclass
  • 12. MOP Method Injection ▷ Injecting methods at code-writing time ▷ We can “open” a class any time ▷ Different techniques: – MetaClass – Categories – Extensions – Mixins vs Traits
  • 13. class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } String chuckIpsum = "If you can see Chuck Norris, he can see you. If you can not see Chuck Norris you may be only seconds away from death" println StringUtils.truncate(chuckIpsum, 72) println StringUtils.truncate(chuckIpsum, 72, true) // Execution If you can see Chuck Norris, he can see you. If you can not see Chuck No If you can see Chuck Norris, he can see you. If you can not see Chuck No... String.metaClass.truncate = { Integer length, Boolean overflow = false -> delegate.take(length) + (overflow ? '...' : '') } assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true) Adding methods using MetaClass
  • 14. class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } String chuckIpsum = "If you can see Chuck Norris, he can see you. If you can not see Chuck Norris you may be only seconds away from death" println StringUtils.truncate(chuckIpsum, 72) println StringUtils.truncate(chuckIpsum, 72, true) // Execution If you can see Chuck Norris, he can see you. If you can not see Chuck No If you can see Chuck Norris, he can see you. If you can not see Chuck No... String.metaClass.truncate = { Integer length, Boolean overflow = false -> delegate.take(length) + (overflow ? '...' : '') } assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true) Adding methods using MetaClass
  • 15. class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } String chuckIpsum = "If you can see Chuck Norris, he can see you. If you can not see Chuck Norris you may be only seconds away from death" println StringUtils.truncate(chuckIpsum, 72) println StringUtils.truncate(chuckIpsum, 72, true) // Execution If you can see Chuck Norris, he can see you. If you can not see Chuck No If you can see Chuck Norris, he can see you. If you can not see Chuck No... String.metaClass.truncate = { Integer length, Boolean overflow = false -> delegate.take(length) + (overflow ? '...' : '') } assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true) Adding methods using MetaClass
  • 16. class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } String chuckIpsum = "If you can see Chuck Norris, he can see you. If you can not see Chuck Norris you may be only seconds away from death" println StringUtils.truncate(chuckIpsum, 72) println StringUtils.truncate(chuckIpsum, 72, true) // Execution If you can see Chuck Norris, he can see you. If you can not see Chuck No If you can see Chuck Norris, he can see you. If you can not see Chuck No... String.metaClass.truncate = { Integer length, Boolean overflow = false -> delegate.take(length) + (overflow ? '...' : '') } assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true) Adding methods using MetaClass
  • 17. class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } String chuckIpsum = "If you can see Chuck Norris, he can see you. If you can not see Chuck Norris you may be only seconds away from death" println StringUtils.truncate(chuckIpsum, 72) println StringUtils.truncate(chuckIpsum, 72, true) // Execution If you can see Chuck Norris, he can see you. If you can not see Chuck No If you can see Chuck Norris, he can see you. If you can not see Chuck No... String.metaClass.truncate = { Integer length, Boolean overflow = false -> delegate.take(length) + (overflow ? '...' : '') } assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true) Adding methods using MetaClass
  • 18. class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } String chuckIpsum = "If you can see Chuck Norris, he can see you. If you can not see Chuck Norris you may be only seconds away from death" println StringUtils.truncate(chuckIpsum, 72) println StringUtils.truncate(chuckIpsum, 72, true) // Execution If you can see Chuck Norris, he can see you. If you can not see Chuck No If you can see Chuck Norris, he can see you. If you can not see Chuck No... String.metaClass.truncate = { Integer length, Boolean overflow = false -> delegate.take(length) + (overflow ? '...' : '') } assert chuckIpsum.truncate(72, true) == StringUtils.truncate(chuckIpsum, 72, true) Adding methods using MetaClass
  • 19. class Utils { } def utilsInstance = new Utils() Utils.metaClass.version = "3.0" utilsInstance.metaClass.released = true assert utilsInstance.version == "3.0" assert utilsInstance.released == true Adding properties using MetaClass
  • 20. Adding properties using MetaClass class Utils { } def utilsInstance = new Utils() Utils.metaClass.version = "3.0" utilsInstance.metaClass.released = true assert utilsInstance.version == "3.0" assert utilsInstance.released == true
  • 21. class Utils { } def utilsInstance = new Utils() Utils.metaClass.version = "3.0" utilsInstance.metaClass.released = true assert utilsInstance.version == "3.0" assert utilsInstance.released == true Adding properties using MetaClass
  • 22. class Utils { } def utilsInstance = new Utils() Utils.metaClass.version = "3.0" utilsInstance.metaClass.released = true assert utilsInstance.version == "3.0" assert utilsInstance.released == true Adding properties using MetaClass
  • 23. // Integer assert '42' == 42.toString() Integer.metaClass.toString = { delegate == 42 ? 'The answer to life, the universe and everything' : String.valueOf(delegate) } assert 42.toString() == 'The answer to life, the universe and everything' assert 100.toString() == '100' // Boolean assert false.toBoolean() == false Boolean.metaClass.toBoolean = { !delegate } assert false.toBoolean() == true Overriding methods using MetaClass
  • 24. // Integer assert '42' == 42.toString() Integer.metaClass.toString = { delegate == 42 ? 'The answer to life, the universe and everything' : String.valueOf(delegate) } assert 42.toString() == 'The answer to life, the universe and everything' assert 100.toString() == '100' // Boolean assert false.toBoolean() == false Boolean.metaClass.toBoolean = { !delegate } assert false.toBoolean() == true Overriding methods using MetaClass
  • 25. // Integer assert '42' == 42.toString() Integer.metaClass.toString = { delegate == 42 ? 'The answer to life, the universe and everything' : String.valueOf(delegate) } assert 42.toString() == 'The answer to life, the universe and everything' assert 100.toString() == '100' // Boolean assert false.toBoolean() == false Boolean.metaClass.toBoolean = { !delegate } assert false.toBoolean() == true Overriding methods using MetaClass
  • 26. // Integer assert '42' == 42.toString() Integer.metaClass.toString = { delegate == 42 ? 'The answer to life, the universe and everything' : String.valueOf(delegate) } assert 42.toString() == 'The answer to life, the universe and everything' assert 100.toString() == '100' // Boolean assert false.toBoolean() == false Boolean.metaClass.toBoolean = { !delegate } assert false.toBoolean() == true Overriding methods using MetaClass
  • 27. // Integer assert '42' == 42.toString() Integer.metaClass.toString = { delegate == 42 ? 'The answer to life, the universe and everything' : String.valueOf(delegate) } assert 42.toString() == 'The answer to life, the universe and everything' assert 100.toString() == '100' // Boolean assert false.toBoolean() == false Boolean.metaClass.toBoolean = { !delegate } assert false.toBoolean() == true Overriding methods using MetaClass
  • 28. // Integer assert '42' == 42.toString() Integer.metaClass.toString = { delegate == 42 ? 'The answer to life, the universe and everything' : String.valueOf(delegate) } assert 42.toString() == 'The answer to life, the universe and everything' assert 100.toString() == '100' // Boolean assert false.toBoolean() == false Boolean.metaClass.toBoolean = { !delegate } assert false.toBoolean() == true Overriding methods using MetaClass
  • 29. Categories ▷ MetaClass changes are “persistent” ▷ Change metaclass in confined code ▷ MOP modified only in the closure
  • 30. Categories example class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } use (StringUtils) { println "Lorem ipsum".truncate(5) } try { println "Lorem ipsum".truncate(5) } catch (MissingMethodException mme) { println mme } // Execution Lorem groovy.lang.MissingMethodException: No signature of method: java.lang.String.truncate() is applicable for argument types: (java.lang.Integer) values: [5] Possible solutions: concat(java.lang.String), take(int)
  • 31. Categories example class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } use (StringUtils) { println "Lorem ipsum".truncate(5) } try { println "Lorem ipsum".truncate(5) } catch (MissingMethodException mme) { println mme } // Execution Lorem groovy.lang.MissingMethodException: No signature of method: java.lang.String.truncate() is applicable for argument types: (java.lang.Integer) values: [5] Possible solutions: concat(java.lang.String), take(int)
  • 32. Categories example class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } use (StringUtils) { println "Lorem ipsum".truncate(5) } try { println "Lorem ipsum".truncate(5) } catch (MissingMethodException mme) { println mme } // Execution Lorem groovy.lang.MissingMethodException: No signature of method: java.lang.String.truncate() is applicable for argument types: (java.lang.Integer) values: [5] Possible solutions: concat(java.lang.String), take(int)
  • 33. Categories example class StringUtils { static String truncate(String text, Integer length, Boolean overflow = false) { text.take(length) + (overflow ? '...' : '') } } use (StringUtils) { println "Lorem ipsum".truncate(5) } try { println "Lorem ipsum".truncate(5) } catch (MissingMethodException mme) { println mme } // Execution Lorem groovy.lang.MissingMethodException: No signature of method: java.lang.String.truncate() is applicable for argument types: (java.lang.Integer) values: [5] Possible solutions: concat(java.lang.String), take(int)
  • 34. Categories example (II) import groovy.time.TimeCategory use (TimeCategory) { println (20.hours + 10.days.from.now) // Fri Jul 17 20:00:00 CEST 2015 } println TimeCategory.getHours(20).plus(TimeCategory.getDays(10).from.now) // Fri Jul 17 20:00:00 CEST 2015
  • 35. Categories example (II) import groovy.time.TimeCategory use (TimeCategory) { println (20.hours + 10.days.from.now) // Fri Jul 17 20:00:00 CEST 2015 } println TimeCategory.getHours(20).plus(TimeCategory.getDays(10).from.now) // Fri Jul 17 20:00:00 CEST 2015
  • 36. Extension modules ▷ JAR file that provides extra methods ▷ Meta-information file ▷ Put jar in classpath to enhance classes
  • 37. // src/main/groovy/londonggug/StringUtilsExtension.groovy package londonggug class StringUtilsExtension { static String truncate(String self, Integer length, Boolean overflow = false) { self.take(length) + (overflow ? '...' : '') } } // Execute with: // gradle build // groovy -cp build/libs/string- extensions-1.0.jar ExtensionExample1.groovy assert "Lorem..." == "Lorem ipsum". truncate(5, true) # src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule moduleName = string-utils-module moduleVersion = 0.1 extensionClasses = londonggug.StringUtilsExtension Extension modules example package londonggug import spock.lang.Specification class StringUtilsExtensionSpec extends Specification { void 'test trucate'() { expect: "Lorem" == "Lorem ipsum".truncate(5) "Lorem..." == "Lorem ipsum".truncate(5, true) } }
  • 38. Extension modules example // src/main/groovy/londonggug/StringUtilsExtension.groovy package londonggug class StringUtilsExtension { static String truncate(String self, Integer length, Boolean overflow = false) { self.take(length) + (overflow ? '...' : '') } } # src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule moduleName = string-utils-module moduleVersion = 0.1 extensionClasses = londonggug.StringUtilsExtension // Execute with: // gradle build // groovy -cp build/libs/string- extensions-1.0.jar ExtensionExample1.groovy assert "Lorem..." == "Lorem ipsum". truncate(5, true) package londonggug import spock.lang.Specification class StringUtilsExtensionSpec extends Specification { void 'test trucate'() { expect: "Lorem" == "Lorem ipsum".truncate(5) "Lorem..." == "Lorem ipsum".truncate(5, true) } }
  • 39. Extension modules example // src/main/groovy/londonggug/StringUtilsExtension.groovy package londonggug class StringUtilsExtension { static String truncate(String self, Integer length, Boolean overflow = false) { self.take(length) + (overflow ? '...' : '') } } // Execute with: // gradle build // groovy -cp build/libs/string- extensions-1.0.jar ExtensionExample1.groovy assert "Lorem..." == "Lorem ipsum". truncate(5, true) # src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule moduleName = string-utils-module moduleVersion = 0.1 extensionClasses = londonggug.StringUtilsExtension package londonggug import spock.lang.Specification class StringUtilsExtensionSpec extends Specification { void 'test trucate'() { expect: "Lorem" == "Lorem ipsum".truncate(5) "Lorem..." == "Lorem ipsum".truncate(5, true) } }
  • 40. Extension modules example // src/main/groovy/londonggug/StringUtilsExtension.groovy package londonggug class StringUtilsExtension { static String truncate(String self, Integer length, Boolean overflow = false) { self.take(length) + (overflow ? '...' : '') } } // Execute with: // gradle build // groovy -cp build/libs/string- extensions-1.0.jar ExtensionExample1.groovy assert "Lorem..." == "Lorem ipsum". truncate(5, true) # src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule moduleName = string-utils-module moduleVersion = 0.1 extensionClasses = londonggug.StringUtilsExtension package londonggug import spock.lang.Specification class StringUtilsExtensionSpec extends Specification { void 'test trucate'() { expect: "Lorem" == "Lorem ipsum".truncate(5) "Lorem..." == "Lorem ipsum".truncate(5, true) } }
  • 41. // src/main/groovy/londonggug/StringUtilsExtension.groovy package londonggug class StringUtilsExtension { static String truncate(String self, Integer length, Boolean overflow = false) { self.take(length) + (overflow ? '...' : '') } } package londonggug import spock.lang.Specification class StringUtilsExtensionSpec extends Specification { void 'test trucate'() { expect: "Lorem" == "Lorem ipsum".truncate(5) "Lorem..." == "Lorem ipsum".truncate(5, true) } } // Execute with: // gradle build // groovy -cp build/libs/string- extensions-1.0.jar ExtensionExample1.groovy assert "Lorem..." == "Lorem ipsum". truncate(5, true) Extension modules example # src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule moduleName = string-utils-module moduleVersion = 0.1 extensionClasses = londonggug.StringUtilsExtension
  • 42. Mixins ▷ “Bring in” or “mix in” implementations from multiple classes ▷ Calls first routed to mixed-in class ▷ Last mixin wins ▷ Not easily un-done
  • 43. class SpidermanPower { String spiderSense() { "Using spider-sense..." } } Mixins example @Mixin([SpidermanPower]) class Person {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert !(person instanceof SpidermanPower) Person.mixin SupermanPower assert person.fly() == "Flying..." assert !(person instanceof SupermanPower) class SupermanPower { String fly() { "Flying..." } }
  • 44. @Mixin([SpidermanPower]) class Person {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert !(person instanceof SpidermanPower) Person.mixin SupermanPower assert person.fly() == "Flying..." assert !(person instanceof SupermanPower) class SupermanPower { String fly() { "Flying..." } } class SpidermanPower { String spiderSense() { "Using spider-sense..." } } Mixins example
  • 45. @Mixin([SpidermanPower]) class Person {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert !(person instanceof SpidermanPower) Person.mixin SupermanPower assert person.fly() == "Flying..." assert !(person instanceof SupermanPower) class SupermanPower { String fly() { "Flying..." } } class SpidermanPower { String spiderSense() { "Using spider-sense..." } } Mixins example
  • 46. @Mixin([SpidermanPower]) class Person {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert !(person instanceof SpidermanPower) Person.mixin SupermanPower assert person.fly() == "Flying..." assert !(person instanceof SupermanPower) class SupermanPower { String fly() { "Flying..." } } class SpidermanPower { String spiderSense() { "Using spider-sense..." } } Mixins example
  • 47. @Mixin([SpidermanPower]) class Person {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert !(person instanceof SpidermanPower) Person.mixin SupermanPower assert person.fly() == "Flying..." assert !(person instanceof SupermanPower) class SpidermanPower { String spiderSense() { "Using spider-sense..." } } Mixins example class SupermanPower { String fly() { "Flying..." } }
  • 48. @Mixin([SpidermanPower]) class Person {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert !(person instanceof SpidermanPower) Person.mixin SupermanPower assert person.fly() == "Flying..." assert !(person instanceof SupermanPower) class SpidermanPower { String spiderSense() { "Using spider-sense..." } } Mixins example class SupermanPower { String fly() { "Flying..." } }
  • 49. “When we started fixing mixin bugs we didn't know if they were a bug or a feature, so we removed mixins and add traits. - Jochen Theodorou (Greach 2015 Opening Keynote)
  • 50. Traits ▷ Groovy 2.3+ ▷ Similar to Java 8 default methods ▷ Supported in JDK 6, 7 and 8 ▷ Stateful ▷ Composition over inheritance ▷ Documentation
  • 51. class Person implements SpidermanPower {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert person instanceof SpidermanPower def person2 = person.withTraits SupermanPower assert person2.fly() == "Flying..." assert person2 instanceof SupermanPower Traits example trait SpidermanPower { String spiderSense() { "Using spider-sense..." } } trait SupermanPower { String fly() { "Flying..." } }
  • 52. class Person implements SpidermanPower {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert person instanceof SpidermanPower def person2 = person.withTraits SupermanPower assert person2.fly() == "Flying..." assert person2 instanceof SupermanPower Traits example trait SpidermanPower { String spiderSense() { "Using spider-sense..." } } trait SupermanPower { String fly() { "Flying..." } }
  • 53. class Person implements SpidermanPower {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert person instanceof SpidermanPower def person2 = person.withTraits SupermanPower assert person2.fly() == "Flying..." assert person2 instanceof SupermanPower Traits example trait SpidermanPower { String spiderSense() { "Using spider-sense..." } } trait SupermanPower { String fly() { "Flying..." } }
  • 54. class Person implements SpidermanPower {} def person = new Person() assert person.spiderSense() == "Using spider-sense..." assert person instanceof SpidermanPower def person2 = person.withTraits SupermanPower assert person2.fly() == "Flying..." assert person2 instanceof SupermanPower Traits example trait SpidermanPower { String spiderSense() { "Using spider-sense..." } } trait SupermanPower { String fly() { "Flying..." } }
  • 56. MOP Method Synthesis ▷ Dynamically figure out behaviour upon invocation ▷ It may not exist until it's called/executed ▷ “Intercept, Cache, Invoke” pattern
  • 57. def p = new Person(name: 'Iván', age: 34) assert p.respondsTo('sayHi') assert p.respondsTo('sayHiTo', String) assert !p.respondsTo('goodbye') assert p.hasProperty('name') assert !p.hasProperty('country') Check for methods and properties class Person { String name Integer age String sayHi() { "Hi, my name is ${name} and I'm ${age}" } String sayHiTo(String name) { "Hi ${name}, how are you?" } }
  • 58. def p = new Person(name: 'Iván', age: 35) assert p.respondsTo('sayHi') assert p.respondsTo('sayHiTo', String) assert !p.respondsTo('goodbye') assert p.hasProperty('age') assert !p.hasProperty('country') Check for methods and properties class Person { String name Integer age String sayHi() { "Hi, my name is ${name} and I'm ${age}" } String sayHiTo(String name) { "Hi ${name}, how are you?" } }
  • 59. Check for methods and properties class Person { String name Integer age String sayHi() { "Hi, my name is ${name} and I'm ${age}" } String sayHiTo(String name) { "Hi ${name}, how are you?" } } def p = new Person(name: 'Iván', age: 35) assert p.respondsTo('sayHi') assert p.respondsTo('sayHiTo', String) assert !p.respondsTo('goodbye') assert p.hasProperty('age') assert !p.hasProperty('country')
  • 60. Check for methods and properties class Person { String name Integer age String sayHi() { "Hi, my name is ${name} and I'm ${age}" } String sayHiTo(String name) { "Hi ${name}, how are you?" } } def p = new Person(name: 'Iván', age: 35) assert p.respondsTo('sayHi') assert p.respondsTo('sayHiTo', String) assert !p.respondsTo('goodbye') assert p.hasProperty('age') assert !p.hasProperty('country')
  • 61. MethodMissing example ▷ Requirements: – Send notifications to users by different channels – +50 notifications – Not all notifications by all channels – Extensible and open to future modifications
  • 62. MethodMissing example abstract class Channel { void sendNewFollower(String username, String follower) { } void sendNewMessage(String username, String msg) { } ... } class EmailChannel extends Channel { void sendNewFollower(String username, String follower) { println "Sending email notification to '${username}' for new follower '${follower}'" } void sendNewMessage(String username, String msg) { println "Sending email notification to '${username}' for new message '${msg}'" } } class MobilePushChannel extends Channel { void sendNewFollower(String username, String follower) { println "Sending mobile push notification to '${username}' for new follower '${follower}'" } }
  • 63. MethodMissing example abstract class Channel { void sendNewFollower(String username, String follower) { } void sendNewMessage(String username, String msg) { } ... } class EmailChannel extends Channel { void sendNewFollower(String username, String follower) { println "Sending email notification to '${username}' for new follower '${follower}'" } void sendNewMessage(String username, String msg) { println "Sending email notification to '${username}' for new message '${msg}'" } } class MobilePushChannel extends Channel { void sendNewFollower(String username, String follower) { println "Sending mobile push notification to '${username}' for new follower '${follower}'" } }
  • 64. MethodMissing example abstract class Channel { void sendNewFollower(String username, String follower) { } void sendNewMessage(String username, String msg) { } ... } class EmailChannel extends Channel { void sendNewFollower(String username, String follower) { println "Sending email notification to '${username}' for new follower '${follower}'" } void sendNewMessage(String username, String msg) { println "Sending email notification to '${username}' for new message '${msg}'" } } class MobilePushChannel extends Channel { void sendNewFollower(String username, String follower) { println "Sending mobile push notification to '${username}' for new follower '${follower}'" } }
  • 65. MethodMissing example abstract class Channel { void sendNewFollower(String username, String follower) { } void sendNewMessage(String username, String msg) { } ... } class EmailChannel extends Channel { void sendNewFollower(String username, String follower) { println "Sending email notification to '${username}' for new follower '${follower}'" } void sendNewMessage(String username, String msg) { println "Sending email notification to '${username}' for new message '${msg}'" } } class MobilePushChannel extends Channel { void sendNewFollower(String username, String follower) { println "Sending mobile push notification to '${username}' for new follower '${follower}'" } }
  • 66. MethodMissing example class NotificationService { List channels = [] def methodMissing(String name, args) { System.out.println "...methodMissing called for ${name} with args ${args}" // Generate the implementation def implementation = { Object[] methodArgs -> channels.each { channel -> def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs) return metaMethod.invoke(channel, methodArgs) } } // Cache the implementation in the metaClass NotificationService instance = this instance.metaClass."$name" = implementation // Execute it! implementation(args) } }
  • 67. MethodMissing example class NotificationService { List channels = [] def methodMissing(String name, args) { System.out.println "...methodMissing called for ${name} with args ${args}" // Generate the implementation def implementation = { Object[] methodArgs -> channels.each { channel -> def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs) return metaMethod.invoke(channel, methodArgs) } } // Cache the implementation in the metaClass NotificationService instance = this instance.metaClass."$name" = implementation // Execute it! implementation(args) } }
  • 68. MethodMissing example class NotificationService { List channels = [] def methodMissing(String name, args) { System.out.println "...methodMissing called for ${name} with args ${args}" // Generate the implementation def implementation = { Object[] methodArgs -> channels.each { channel -> def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs) return metaMethod.invoke(channel, methodArgs) } } // Cache the implementation in the metaClass NotificationService instance = this instance.metaClass."$name" = implementation // Execute it! implementation(args) } } notificationService.sendNewFollower(...) notificationService.sendNewMessage(...)
  • 69. MethodMissing example class NotificationService { List channels = [] def methodMissing(String name, args) { System.out.println "...methodMissing called for ${name} with args ${args}" // Generate the implementation def implementation = { Object[] methodArgs -> channels.each { channel -> def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs) return metaMethod.invoke(channel, methodArgs) } } // Cache the implementation in the metaClass NotificationService instance = this instance.metaClass."$name" = implementation // Execute it! implementation(args) } }
  • 70. MethodMissing example class NotificationService { List channels = [] def methodMissing(String name, args) { System.out.println "...methodMissing called for ${name} with args ${args}" // Generate the implementation def implementation = { Object[] methodArgs -> channels.each { channel -> def metaMethod = channel.metaClass.getMetaMethod(name, methodArgs) return metaMethod.invoke(channel, methodArgs) } } // Cache the implementation in the metaClass NotificationService instance = this instance.metaClass."$name" = implementation // Execute it! implementation(args) } }
  • 71. MethodMissing example // Execution ...methodMissing called for sendNewFollower with args [John, Peter] Sending email notification to 'John' for new follower 'Peter' Sending mobile push notification to 'John' for new follower 'Peter' Sending email notification to 'Mary' for new follower 'Steve' Sending mobile push notification to 'Mary' for new follower 'Steve' ...methodMissing called for sendNewMessage with args [Iván, Hello!] Sending email notification to 'Iván' for new message 'Hello!' def notificationService = new NotificationService( channels: [new EmailChannel(), new MobilePushChannel()] ) assert !notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("John", "Peter") assert notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("Mary", "Steve") notificationService.sendNewMessage("Iván", "Hello!")
  • 72. MethodMissing example // Execution ...methodMissing called for sendNewFollower with args [John, Peter] Sending email notification to 'John' for new follower 'Peter' Sending mobile push notification to 'John' for new follower 'Peter' Sending email notification to 'Mary' for new follower 'Steve' Sending mobile push notification to 'Mary' for new follower 'Steve' ...methodMissing called for sendNewMessage with args [Iván, Hello!] Sending email notification to 'Iván' for new message 'Hello!' def notificationService = new NotificationService( channels: [new EmailChannel(), new MobilePushChannel()] ) assert !notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("John", "Peter") assert notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("Mary", "Steve") notificationService.sendNewMessage("Iván", "Hello!")
  • 73. MethodMissing example // Execution ...methodMissing called for sendNewFollower with args [John, Peter] Sending email notification to 'John' for new follower 'Peter' Sending mobile push notification to 'John' for new follower 'Peter' Sending email notification to 'Mary' for new follower 'Steve' Sending mobile push notification to 'Mary' for new follower 'Steve' ...methodMissing called for sendNewMessage with args [Iván, Hello!] Sending email notification to 'Iván' for new message 'Hello!' def notificationService = new NotificationService( channels: [new EmailChannel(), new MobilePushChannel()] ) assert !notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("John", "Peter") assert notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("Mary", "Steve") notificationService.sendNewMessage("Iván", "Hello!")
  • 74. MethodMissing example // Execution ...methodMissing called for sendNewFollower with args [John, Peter] Sending email notification to 'John' for new follower 'Peter' Sending mobile push notification to 'John' for new follower 'Peter' Sending email notification to 'Mary' for new follower 'Steve' Sending mobile push notification to 'Mary' for new follower 'Steve' ...methodMissing called for sendNewMessage with args [Iván, Hello!] Sending email notification to 'Iván' for new message 'Hello!' def notificationService = new NotificationService( channels: [new EmailChannel(), new MobilePushChannel()] ) assert !notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("John", "Peter") assert notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("Mary", "Steve") notificationService.sendNewMessage("Iván", "Hello!")
  • 75. MethodMissing example // Execution ...methodMissing called for sendNewFollower with args [John, Peter] Sending email notification to 'John' for new follower 'Peter' Sending mobile push notification to 'John' for new follower 'Peter' Sending email notification to 'Mary' for new follower 'Steve' Sending mobile push notification to 'Mary' for new follower 'Steve' ...methodMissing called for sendNewMessage with args [Iván, Hello!] Sending email notification to 'Iván' for new message 'Hello!' def notificationService = new NotificationService( channels: [new EmailChannel(), new MobilePushChannel()] ) assert !notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("John", "Peter") assert notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("Mary", "Steve") notificationService.sendNewMessage("Iván", "Hello!")class EmailChannel extends Channel { void sendNewFollower(String username, String follower) {…} void sendNewMessage(String username, String msg) {…} } class MobilePushChannel extends Channel { void sendNewFollower(String username, String follower) {…} }
  • 76. MethodMissing example // Execution ...methodMissing called for sendNewFollower with args [John, Peter] Sending email notification to 'John' for new follower 'Peter' Sending mobile push notification to 'John' for new follower 'Peter' Sending email notification to 'Mary' for new follower 'Steve' Sending mobile push notification to 'Mary' for new follower 'Steve' ...methodMissing called for sendNewMessage with args [Iván, Hello!] Sending email notification to 'Iván' for new message 'Hello!' def notificationService = new NotificationService( channels: [new EmailChannel(), new MobilePushChannel()] ) assert !notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("John", "Peter") assert notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("Mary", "Steve") notificationService.sendNewMessage("Iván", "Hello!")
  • 77. MethodMissing example // Execution ...methodMissing called for sendNewFollower with args [John, Peter] Sending email notification to 'John' for new follower 'Peter' Sending mobile push notification to 'John' for new follower 'Peter' Sending email notification to 'Mary' for new follower 'Steve' Sending mobile push notification to 'Mary' for new follower 'Steve' ...methodMissing called for sendNewMessage with args [Iván, Hello!] Sending email notification to 'Iván' for new message 'Hello!' def notificationService = new NotificationService( channels: [new EmailChannel(), new MobilePushChannel()] ) assert !notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("John", "Peter") assert notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("Mary", "Steve") notificationService.sendNewMessage("Iván", "Hello!")
  • 78. MethodMissing example def notificationService = new NotificationService( channels: [new EmailChannel(), new MobilePushChannel()] ) assert !notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("John", "Peter") assert notificationService.respondsTo('sendNewFollower', String, String) notificationService.sendNewFollower("Mary", "Steve") notificationService.sendNewMessage("Iván", "Hello!") // Execution ...methodMissing called for sendNewFollower with args [John, Peter] Sending email notification to 'John' for new follower 'Peter' Sending mobile push notification to 'John' for new follower 'Peter' Sending email notification to 'Mary' for new follower 'Steve' Sending mobile push notification to 'Mary' for new follower 'Steve' ...methodMissing called for sendNewMessage with args [Iván, Hello!] Sending email notification to 'Iván' for new message 'Hello!'
  • 79. 2. Why we should use metaprogramming?
  • 80. Let’s review some concepts Metaprogramming out-of-the box Easy and very powerful Write better code Add behaviour easily Take advantage of this power Because Groovy, it's groovy
  • 81. With great power comes great responsibility