GR8Conf 2009: What's New in Groovy 1.6? by Guillaume Laforge

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Guillaume Laforge, Groovy Project Manager, present the new features and improvements in Groovy 1.6.

Guillaume Laforge, Groovy Project Manager, present the new features and improvements in Groovy 1.6.

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  • 1. What’s new in Groovy 1.6? Get started with Groovy and learn about all the novelties in the latest release Guillaume Laforge Head of Groovy Development
  • 2. 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… 3
  • 3. 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 4
  • 4. nda Ag e > 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 5
  • 5. Groovy in a Nutshell Simplify the Life of Java Developers > Groovy is a dynamic language for the JVM  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 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() ); } } 7
  • 7. A Taste of Groovy — Take 2 A Normal 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() ); } } 8
  • 8. A Taste of Groovy — Take 3 A Groovier Program > class HelloWorld { String name String greet() { "Hello $name" } } def helloWorld = new HelloWorld(name: "Groovy") println helloWorld.greet() 9
  • 9. The Groovy Web Console A Groovy Playground > Groovy works nicely on Google App Engine  You can also deploy Grails applications > You can play with Groovy in the web console  http://groovyconsole.appspot.com/ 10
  • 10. The Groovy Web Console A Screenshot 11
  • 11. Features at a Glance > Fully Object-Oriented > Joint compiler: seamless Java integration > Closures: reusable blocks of code / anon functions > Properties: forget about getters and setters > Optional typing: your choice! > BigDecimal arithmetic by default for floating point > Handy APIs  XML, JDBC, JMX, template engine, Swing UIs > Strong ability for authoring Domain-Specific Languages  Syntax-level “builders”  Adding properties to numbers: 10.dollars  Operator overloading: 10.meters + 20.kilometers 12
  • 12. Joint Compilation • Total Java interoperability • Concretely, what does it mean? JInterface GInterface <<implements>> <<implements>> GClass JClass JClass GClass 13
  • 13. Native Syntax Constructs • Lists – def numbers = [1, 2, 3, 4, 5] • Maps – def map = [FR: ‘France’, BE: ‘Belgium’] • Ranges – def allowed = 18..65 • Regular expressions – def whitespace = ~/s+?/ – if (‘foo’ ==~ /o+/) { ... } 14
  • 14. GStrings! • GStrings are... interpolated strings – Sorry, not really what you expected! – Placeholder variables are replaced – You can have multiline strings • def person = ‘John’ def letter = “““${new Date()} Dear ${person}, I hope you’re fine! ””” 15
  • 15. Closures • Closures are reusable and assignable code blocks or anonymous functions – No need to wait for Java 7/8/9 to get them! – def greet = { println “Hello ${it}” } greet(“Guillaume”) • You can pass parameters – def greet = { String name -> println “Hello ${name}” } • You can passe closures around – def method(Closure c) { c(“Hello”) } method(greet) 16
  • 16. BigDecimal Arithmetic • Main reason why financial institutions often decide to use Groovy for their business rules! – Although these days rounding issues are overrated! • Java vs Groovy for a simple interpolation equation • BigDecimal uMinusv = c.subtract(a); BigDecimal vMinusl = b.subtract(c); BigDecimal uMinusl = a.subtract(b); return e.multiply(uMinusv) .add(d.multiply(vMinusl)) .divide(uMinusl, 10, BigDecimal.ROUND_HALF_UP); • (d * (b - c) + e * (c - a)) / (a - b) 17
  • 17. Groovy Builders • The Markup builder – Easy way for creating XML or HTML content – def mkp = new MarkupBuilder() mkp.html { head { title “Groovy in Action” } body { div(width: ‘100’) { p(class: ‘para’) { span “Best book ever!” } } } } 18
  • 18. Parsing XML • And it’s so easy to parser XML and navigate through the node graph! • def geocodingUrl = "http://...".toURL() geocodingUrl.withInputStream { stream -> def node = new XmlSlurper().parse(stream) if (node.Response.Status.code == "200") { def text = node.Response.Placemark. Point.coordinates.text() def coord = text.tokenize(','). collect{ Float.parseFloat(it) } (latitude, longitude) = coord[1..0] } } 19
  • 19. nda Ag e > 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 20
  • 20. 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 21
  • 21. nda Ag e > 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 22
  • 22. 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 23
  • 23. 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 24
  • 24. 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… 25
  • 25. nda Ag e > 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 26
  • 26. 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 27
  • 27. AST Transformations in 1.6 Implement Patterns through Transformations > Several transformations find their way in Groovy 1.6  @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! 28
  • 28. @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 {} 29
  • 29. @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 30
  • 30. @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 31
  • 31. @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… 32
  • 32. nda Ag e > 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 33
  • 33. 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() } 34
  • 34. nda Ag e > 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 35
  • 35. @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); } } 36
  • 36. @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 37
  • 37. Griffon The Swing MVC Framework > Leverages Groovy’s SwingBuilder and Grails’ infrastructure  http://griffon.codehaus.org 38
  • 38. 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 39
  • 39. 40
  • 40. nda Ag e > 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 41
  • 41. 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) } } 42
  • 42. 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!" 43
  • 43. nda Ag e > 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 44
  • 44. javax.script.* Scripting APIs Groovy Scripting Engine Built-In > The JSR-223 / javax.script.* scripting engine for Groovy is bundled in Groovy 1.6  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! 45
  • 45. nda Ag e > 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 46
  • 46. 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 47
  • 47. JMX Builder (2/2) Domain-Specific Language for JMX > 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 -> …}) 48
  • 48. nda Ag e > 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 49
  • 49. 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 50
  • 50. Summary
  • 51. Summary Just Remember that Groovy Rocks! :-) > Any Java developer is a Groovy developer! > Great for your next-generation general purpose programming language, as well as for admin tasks, extending apps, writing DSLs... > 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 52
  • 52. Questions & Answers