Groovy Powered Clean Code

GROOVY POWERED CLEAN CODE
Noam Tenne

$WHOAMI
Developing on the JVM for the past 13 years
codefresh.io
Altogether standup guy
@NoamTenne
blog.10ne.org

CODEFRESH.IO
Docker oriented CI/CD that goes to 11

CODEFRESH.IO
Build your services as Docker images
(You don’t even need a Dockerﬁle)

CODEFRESH.IO
Instantly launch your services
(Solo or part of a composition)

“Writing clean code is what you must
do in order to call yourself a
professional.”
–Robert C. Martin
http://www.amazon.com/dp/0132350882/ref=cm_sw_r_tw_dp_GuZ2wb1ZS9GXP

ISTHISYOUR REFACTORING SESSION?

MEANINGFUL NAMES
def myItemArrayList = []

FUNCTIONS
breedDogAndPutItThroughAstronautTrainingAndSendItToSpace()

COMMENTS
//Construct object, obviously 
def object = new Obvious()

OBJECTSVS. DATA-STRUCTS
planetSmasher.getPlanetContext().planet = "Earth" 
planetSmasher.smash()

ERROR HANDLING
catch (Exception e) { 
//noop 
}

ScriptEngineManager sem = new ScriptEngineManager(); 
 
ScriptEngine jse = sem.getEngineByName("javascript"); 
String script = "Java.asJSONCompatible(" + json + ")"; 
 
Object rawJsonObject = javascriptEngine.eval(script); 
Map contents = (Map) rawJsonObject;

import groovy.json.JsonSlurper 
…
 
def contents = new JsonSlurper().parse(json)

String html = "<html>";
html += "<head>";
html += "<title>Noam's guide to Copenhagen</title>";
html += "</head>";
...
html += "</body>";
html += "</html>";

new MarkupBuilder(it).html {
head {
title("Noam's Guide To Copenhagen")
}
body {
...
}
}

DocumentBuilderFactory
docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder =
docFactory.newDocumentBuilder();
Document doc = docBuilder.newDocument();
Element rootElement = doc.createElement("gah");
doc.appendChild(rootElement);

def xml = new MarkupBuilder()
xml.guide(type:"guide"){
title("Noam's Guide To Copenhagen")
}

def json = new JsonBuilder()
def root = json {
title "Noam's Guide To Copenhagen"
}
json.toString()

private void readTheStream() {
URI.create("gr8conf.eu").toURL().openStream(); 
}
throws IOException

private void readTheStream() {
URI.create("gr8conf.eu").toURL().openStream(); 
}

WHAT MAKES GROOVY REALLY CLEAN?

import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader; 
…
Reader isr = new InputStreamReader(it);

def isr = new InputStreamReader(it);

DEFAULT IMPORTS
import java.lang.* 
import java.util.* 
import java.io.* 
import java.net.* 
import groovy.lang.* 
import groovy.util.* 
import java.math.BigInteger 
import java.math.BigDecimal

import org.slf4j.* 
import groovy.util.logging.Slf4j 
 
@Slf4j 
class GroovyDoge { 
 
public static void main(String[] args) { 
log.info "Wow! Much Groovy! So Log!" 
} 
}

ASTTRANSFORMATION
1. Initialization
2. Parsing
3. Conversion
4. Semantic Analysis
5. Canonicalization
6. Instruction Selection
7. Class Generation
8. Output
9. Finalization

List list = [] 
assert list instanceof java.util.ArrayList 
list.plus([])

REGISTERED META METHODS
POGO Metaclass
MetaclassRegistry

def fileContents = Paths.get('/path/to/file').text

EXTENSION MODULES
class MyExtension { 
public static String asString(Integer target) { 
... 
} 
}

EXTENSION MODULES
... 
} 
}
Register the class with a descriptor in META-INF/services

EXTENSION MODULES
... 
} 
}
Register the class with a descriptor in META-INF/services
1337.asString()

SCRIPTS
def message = "Much script! Wow! So code!" 
println message

SCRIPTS
import org.codehaus.groovy.runtime.InvokerHelper 
 
class DogeScript extends Script { 
def run() { 
def message = "Much script! Wow! So code!" 
println message 
} 
static void main(String[] args) { 
InvokerHelper.runScript(DogeScript, args) 
} 
}

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