Whats New In Groovy 1.6?

What’s new in Groovy 1.6? Guillaume Laforge Groovy Project Manager / SpringSource

Guillaume Laforge Groovy Project Manager — SpringSource > Working on Groovy since 2003 > JSR-241 Spec Lead > Initiator of the Grails web framework > Co-author of Groovy in Action > Speaker: JavaOne, QCon, JavaPolis/Devoxx, JavaZone, Sun Tech Days, SpringOne/The Spring Experience, JAX, DSL DevCon, and more… 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 2 2

What’s new in Groovy 1.6? Article Published by InfoQ > This presentation was prepared with the examples I’ve used in my article written for InfoQ > http://www.infoq.com/articles/groovy-1-6 > Read this article for more detailed explanations of all the new features in Groovy 1.6 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 3 3

Agenda > Groovy Overview > Performance Improvements > Syntax Enhancements > Compile-Time Metaprogramming > The Grape Module System > Swing-Related Improvements > Runtime Metaprogramming Additions > JSR-223 Scripting Engine Built-In > JMX Builder > OSGi Readiness 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 4 4

Groovy in a Nutshell Simplify the Life of Java Developers > Groovy is a dynamic language for the Java Virtual Machine  With a Meta-Object Protocol  Compiles down to bytecode > Open Source Apache licensed project > Relaxed grammar derived from the Java 5 grammar  Borrowed some good ideas from Smalltalk/Python/Ruby  Java 5 features out of the box: annotations, generics, static imports, enums…  Flat learning curve 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 5 5

Features at a Glance Lots More Than This! > Fully Object-Oriented > Joint compiler: seamless Java integration > Closures: reusable blocks of code / anonymous functions > Properties: forget about getters and setters > Optional typing: your choice! > BigDecimal arithmetic by default for floating point > Handy APIs  XML, JDBC, JMX, template engine, Swing UIs > Strong ability for authoring Domain-Specific Languages  Syntax-level “builders”  Adding properties to numbers: 10.dollars  Operator overloading: 10.meters + 20.kilometers 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 6 6

A Taste of Groovy — Take 1 A Normal Java Program > public class HelloWorld { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } public String greet() { return \"Hello \" + name; } public static void main(String[] args) { HelloWorld helloWorld = new HelloWorld(); helloWorld.setName(\"Groovy\"); System.out.println( helloWorld.greet() ); } } 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 7 7

A Taste of Groovy — Take 2 A Valid Groovy Program > public class HelloWorld { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } public String greet() { return \"Hello \" + name; } public static void main(String[] args) { HelloWorld helloWorld = new HelloWorld(); helloWorld.setName(\"Groovy\"); System.out.println( helloWorld.greet() ); } } 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 8 8

A Taste of Groovy — Take 3 A Groovier Program! > class HelloWorld { String name String greet() { \"Hello $name\" } } def helloWorld = new HelloWorld(name: \"Groovy\") println helloWorld.greet() 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 9 9

The Groovy Web Console A Groovy Playground > Groovy works nicely on Google App Engine  You can also deploy Grails applications > You can play with Groovy in the web console  http://groovyconsole.appspot.com/ 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 10 10

Performance Improvements Both Runtime & Compile-Time > The Groovyc compiler is 3x to 5x faster  With a clever class lookup cache > Certain online micro-benchmarks show 150% to 460% increase in performance compared to Groovy 1.5  Thanks to advanced call-site caching techniques  Beware of micro-benchmarks! > Makes Groovy one of the fastest dynamic languages available 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 12 12

Multiple Assignment Assign Multiple Variables at Once > Newly defined variables  def (a, b) = [1, 2] assert a == 1 assert b == 2 > Assign to existing variables  def lat, lng (lat, lng) = geocode(‘Paris’) > The classical swap case  (a, b) = [b, a] > Extra elements ⇒ not assigned to any variable > Less elements ⇒ null into extra variables 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 14 14

More Optional Return In if/else and try/catch Blocks > The return keyword is optional for the last expression of a method body  But if/else & try/catch didn’t return any value > def method() { if (true) 1 else 0 } assert method() == 1 > def method(bool) { try { if (bool) throw new Exception(\"foo\") 1 } catch(e) { 2 } finally { 3 } } assert method(false) == 1 assert method(true) == 2 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 15 15

Annotation Definition The Missing Bit of Java 5 Support > Groovy support for Java 5 features is now complete with the missing annotation definition > Nothing to show here, it’s just normal Java :-) > Note that the sole dynamic language supporting annotation is… Groovy  Opens the door to EJB3 / JPA / Spring annotations / Guice / TestNG… 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 16 16

Meta-What? Meta-Programming > The ability of a language to modify itself > Groovy 1.6 introduces AST Transformations  Abstract Syntax Tree > Goodbye to a lot of boiler-plate technical code! > Two kinds of transformations  Global transformations  Local transformations: triggered by annotations 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 18 18

AST Transformations in Groovy 1.6 Implement Patterns through Transformations > Several transformations finds their way  @Singleton — okay, not really a pattern ;-)  @Immutable, @Lazy, @Delegate  @Newify  @Category and @Mixin  @PackageScope  Swing’s @Bindable and @Vetoable  Grape’s @Grab > Let’s have a look at some of them! 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 19 19

@Singleton (Anti-)Pattern Revisited > The evil Java singleton  public class Evil { public static final Evil instance = new Evil (); private Evil () {} Evil getInstance() { return instance; } } > In Groovy:  @Singleton class Evil {} > There’s also a « lazy » version  @Singleton(lazy = true) class Evil {} 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 20 20

@Immutable The Immutable… Boiler-Plate Code > To properly implement immutable classes  No mutators (state musn’t change)  Private final fields  Defensive copying of mutable components  Proper equals() / hashCode() / toString() for comparisons or for keys in maps, etc. > In Groovy  @Immutable final class Coordinates { Double lat, lng } def c1 = new Coordinates(lat: 48.8, lng: 2.5) def c2 = new Coordinates(48.8, 2.5) assert c1 == c2 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 21 21

@Lazy Not Just for Lazy Dudes! > When you need to lazy evaluate / instantiate complex data structures for class fields, mark them as @Lazy  class Dude { @Lazy pets = retriveFromSlowDB() } > Groovy will handle the boiler-plate code for you 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 22 22

@Delegate Not Just for Managers! > You can delegate to fields of your class  Think multiple inheritance  class Employee { def doTheWork() { \"done\" } } class Manager { @Delegate Employee slave = new Employee() } def god = new Manager() assert god.doTheWork() == \"done\" > Damn manager who will get all the praise… 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 23 23

Grab a Grape Groovy Advanced Packaging Engine > Helps you distribute scripts without dependencies > Just declare your dependencies with @Grab  Will look for dependencies in Maven or Ivy repositories > @Grab(group = 'org.mortbay.jetty', module = 'jetty-embedded', version = '6.1.0') def startServer() { def srv = new Server(8080) def ctx = new Context(srv , \"/\", SESSIONS); ctx.resourceBase = \".\" ctx.addServlet(GroovyServlet, \"*.groovy\") srv.start() } 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 25 25

@Bindable (1/2) Event-Driven Made Easy > Speaking of boiler-plate code… property change listeners > import java.beans.PropertyChangeSupport; import java.beans.PropertyChangeListener; public class MyBean { private String prop; PropertyChangeSupport pcs = new PropertyChangeSupport(this); public void addPropertyChangeListener(PropertyChangeListener l) { pcs.add(l); } public void removePropertyChangeListener(PropertyChangeListener l) { pcs.remove(l); } public String getProp() { return prop; } public void setProp(String prop) { pcs.firePropertyChanged(\"prop\", this.prop, this.prop = prop); } } 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 27 27

@Bindable (2/2) Event-Driven Made Easy > Groovy’s solution  class MyBean { @Bindable String prop } > Interesting in Griffon and Swing builder  textField text: bind { myBean.prop } > Also of interest: @Vetoable 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 28 28

Griffon The Swing MVC Framework > Leverages Groovy’s SwingBuilder and Grails’ infrastructure  http://griffon.codehaus.org > Don’t miss the Griffon BOF! 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 29 29

Swing Console Improvements > The console can be run as an applet > Code indentation support > Script drag’n drop > Add JARs in the classpath from the GUI > Execution results visualization plugin > Clickable stacktraces and error messages > Not intended to be a full-blown IDE, but handy 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 30 30

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ExpandoMetaClass DSL Less Repetition > EMC is a way to change the behavior of types at runtime > Before  Number.metaClass.multiply = { Amount amount -> amount.times(delegate) } Number.metaClass.div = { Amount amount -> amount.inverse().times(delegate) } > Now in Groovy 1.6  Number.metaClass { multiply { Amount amount -> amount.times(delegate) } div { Amount amount -> amount.inverse().times(delegate) } } 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 33 33

Runtime Mixins Inject New Behavior to Types at Runtime > class FlyingAbility { def fly() { \"I'm ${name} and I fly!\" } } class JamesBondVehicle { String getName() { \"James Bond's vehicle\" } } JamesBondVehicle.mixin FlyingAbility assert new JamesBondVehicle().fly() == \"I'm James Bond's vehicle and I fly!\" 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 34 34

javax.script.* Scripting APIs Groovy Scripting Engine Built-In > In Groovy 1.6, the JSR-223 / javax.script.* scripting engine for Groovy is bundled  import javax.script.* def manager = new ScriptEngineManager() def engine = manager.getEngineByName(\"groovy\") assert engine.evaluate(\"2 + 3\") == 5 > To evaluate Groovy scripts at runtime in your application, just drop the Groovy JAR in your classpath! 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 36 36

JMX Builder (1/2) Domain-Specific Language for JMX > Simplify JMX handling with a Builder pattern approach > Declaratively expose Java/Groovy objects as MBeans > JMX's event model support  Inline closures to create event handler & broadcaster  Closures for receiving event notifications > Provides a flexible registration policy for MBean > Exposes attribute, constructors, operations, parameters, and notifications > Simplified creation of connector servers & clients > Support for exporting JMX timers > http://groovy.codehaus.org/Groovy+JmxBuilder 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 38 38

JMX Builder (2/2) Examples > Create a connector server  def jmx = new JmxBuilder() jmx.connectorServer(port:9000).start() > Create a connector client  jmx.connectorClient(port:9000).connect() > Export a bean  jmx.export { bean new MyService() } > Defining a timer  jmx.timer(name: \"jmx.builder:type=Timer\", event: \"heartbeat\", period: \"1s\").start() > JMX listener  jmx.listener(event: \"…\", from: \"foo\", call: { event -> …}) 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 39 39

OSGi Readiness > The Groovy JAR contains OSGi metadata  Can be reused in OSGi containers out-of-the-box > Tutorials on Groovy and OSGi  http://groovy.codehaus.org/OSGi+and+Groovy  Will show you how to load Groovy as a service, write, publish and consume Groovy services, and more 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 41 41

Summary

Summary Just Remember that Groovy Rocks! :-) > Groovy 1.6 provides  Important performance gains  Efficient compile-time metaprogramming hooks  New useful features (JMX, javax.script.*, etc.)  A script dependencies system  Various Swing-related improvements  Several runtime metaprogramming additions > Get it now!  http://groovy.codehaus.org/Download 2009 CommunityOne Conference: EAST | developers.sun.com/events/communityone 43 43

What’s new in Groovy 1.6? Guillaume Laforge glaforge@gmail.com

Whats New In Groovy 1.6?

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