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Basel Baden Bern Lausanne Zurich Dsseldorf Frankfurt/M. Freiburg i. Br. Hamburg Munich Stuttgart Vienna

GROOVY

Mischa Klliker

Guido Schmutz

Zrich, 24.06.2008

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Groovy - Java Lounge June/2008 2 2008

Agenda

Data are always

part of the game.

Groovy: Java on dope

Builders

Groovy on Windows

What about performance?

Wrap up

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Groovy.compareTo(Java)

GroovyScript.groovyGroovyClass.groovy

GroovyScript.groovyGroovyClass.groovy JavaClass.java

JavaClass.java

javac.exegroovyc.exe

GroovyScript.classGroovyClass.classJavaClass.class

GroovyScript.classGroovyClass.classJavaClass.class

Java Virtual Machine

Java Virtual Machine

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Groovy.compareTo(Java)

Groovy

compiled

dynamic typed

weak typed

"execute" Source

Java

compiled

static typed

weak typed

execute compiledclass only

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Implicit classes

Java:

Groovy basics

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Groovy Collections

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Groovy Maps

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GPath

Java:

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GPath - Groovy

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Closures

Methods without a name

Internally implemented as an inner class with one method

Often, implicit variables like it are available

The last expression will be automatically returned

This is valid for all methods

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Closures with iterators

Work like the body of a for or while loop

Beyond times and each, there is reverseEach, eachMatchfind, findAll, findIndexOf, any, every, grep, collect,collectAll, groupBy, inject, sum,min,max, upTo,downTo, step and more iterating methods which take a closure

Look atorg.codehaus.groovy.runtime.DefaultGroovyMethods

to find out more

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The Meta Object Protocol (MOP)

Caller classCaller class MetaClassMetaClass

"Real class", e.g,

java.util.Date

"Real class", e.g,

java.util.Date

e.g. java.util.Date

Dynamicallyadded

methods and

properties

Dynamicallyadded

methods and

properties

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The MOP: intercept, relay, pretend

Meta ObjectProtocol

The heart ofGroovy

Simulateproperties:

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Pretend properties: usage

There are also get() and set(), only for unknown properties

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Agenda

Data are always

part of the game.


Builders

Groovy on Windows


Wrap up

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Groovy Builders

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Groovy Builders

Builders are a set of nested Closures which

Pretend available methods

Delegate method calls to the builder

Builders are executable configuration

Builders produce their ouput (if any) immediately

Not like config files, which are first parsed and then queried

Also not like a template which can be reused

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Agenda

Data are always

part of the game.


Builders

Groovy on Windows


Wrap up

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Scriptom: Groovy on Windows

Requires a DLL in the path and a JAR in GROOVY_HOME\lib(uses Jacob, the Java COM Bridge)

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Agenda

Data are always

part of the game.


Builders

Groovy on Windows


Wrap up

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Groovy performance: The price of it

Java 71-82ms

Groovy 220-240ms, 3x slower

The dynamic and reflective

nature makes Groovyconsiderably slower than Java

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Groovy performance: how come?

compiles to:

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Groovy performance: Good news

Groovy 1.6 promises 100x speed-up in regard of dynamic calls

JSR 292 adds a new 'invokedynamic' instruction to the JVM

Scheduled for Java 7

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Agenda

Data are always

part of the game.


Builders

Groovy on Windows


Wrap up

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Groovy drawbacks (are there any?)

2..10.times { slower } // than Java

The dynamic nature lacks of compile time security

No safe refactorings

Less useful code completion in IDEs

Scripts: No need to declare variables lead to hard-to-find errors

Test, test, test

The resolver behaviour is sometimes tricky to understand

e.g.: this.class.methods.name // name is a prop of a single method

e.g.:println map[key] // is key a literal string or a variable?

No semicolons Problem with multiline expressions

The last expression is automatically returned

Maybe not what I really want

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Groovy advantages

Very expressive

Short syntax

Easy SQL

Easy trees with builders

Easy integration (e.g. with windows)

Extends Java classes with functionality we always wished to have

Sometimes more compile time security when writing config fileswith builders instead of XML

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Things that didnt made it into this presentation

Groovy XML

Various goodies

Spread operator *. Elvis operator ?: (this is not ? : )

Method reference operator .&

Spaceship operator

File.withWriter { }

RegEx-handling and improvments

Reverse ranges, exclusive ranges (..>)

switch statement and the isCase() method

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Things that didnt made it into this presentation II

GORM: Groovy Object Relational Mapping

Is developed under the hoods of Grails

Dynamically creating and executing classes and scripts

Working with the MetaClass

Groovlets (Groovy Servlets)

Groovy Templating

Groovy WebServices SOAP-Support

REST-Support

XML-RPC

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Things that didnt made it into this presentation III

Groovy and Ant:

AntBuilder,

Groovy-task for Ant, excuting AntScripts withinGroovy

Groovy and Spring

BeanBuilder

groovy namespace in Spring XML

Groovy and Java

Just works as expected

except some class loading issues with various server configurations

Debugging

Currently only if you have plenty of time

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Groovy 1

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