Groovy to infinity and beyond - SpringOne2GX - 2010 - Guillaume Laforge

Chicago, October 19 - 22, 2010

to Infinity and Beyond!

Guillaume Laforge — SpringSource

jeudi 21 octobre 2010

to Infinity and Beyond


Guillaume Laforge

• Groovy Project Manager• JSR-241 Spec Lead• Head of Groovy Development

at SpringSource• Initiator of the Grails framework• Founder of the Gaelyk toolkit• Co-author of Groovy in Action

• Speaker: JavaOne, QCon, JavaZone, Sun TechDays, Devoxx, The Spring Experience, SpringOne2GX, JAX, Dynamic Language World, IJTC, and more...

3jeudi 21 octobre 2010

Bug killer... real insects with legs!

• Thanks to Groovy, with one hand left for coding, I’m still more productive than with Java!


Bug killer... real insects with legs!

• Thanks to Groovy, with one hand left for coding, I’m still more productive than with Java!


SpringOne 2GX 2010. All rights reserved. Do not distribute without permission.

Agenda


Agenda

• Past– Groovy 1.6 flashback

• Present– Groovy 1.7 novelties– A few Groovy 1.7.x refinements

• Future– What’s cooking for 1.8 and beyond


looking into the Pastjeudi 21 octobre 2010

Big highlights of Groovy 1.6

• Greater compile-time and runtime performance• Multiple assignments• Optional return for if/else and try/catch/finally• Java 5 annotation definition• AST Transformations• The Grape module and dependency system• Various Swing related improvements• JMX Builder• Metaprogramming additions• JSR-223 scripting engine built-in• Out-of-the-box OSGi support


Multiple assignement

// multiple assignmentdef (a, b) = [1, 2]assert a == 1 && b == 2

// with typed variablesdef (int c, String d) = [3, "Hi"]assert c == 3 && d == "Hi"

def geocode(String place) { [48.8, 2.3] }def lat, lng// assignment to existing variables(lat, lng) = geocode('Paris')

// classical variable swaping example(a, b) = [b, a]


More optional return

// optional return for if statements

def m1() { if (true) 1 else 0}assert m1() == 1

// optional return for try/catch/finally

def m2(bool) { try { if (bool) throw new Exception()

1 } catch (any) { 2 } finally { 3 }}assert m2(true) == 2 && m2(false) == 1


AST Transformation (1/2)

• Groovy 1.6 introduced AST Transformations• AST: Abstract Syntax Tree• Ability to change what’s being compiled by the Groovy

compiler... at compile time– No runtime impact!– Change the semantics of your programs! Even hijack the Groovy

syntax!– Implementing recurring patterns in your code base– Remove boiler-plate code

• Two kinds: global and local (triggered by anno)


AST Transformations (2/2)

• Transformations introduced in 1.6– @Singleton– @Immutable, @Lazy, @Delegate– @Newify– @Category, @Mixin– @PackageScope– Swing’s @Bindable and @Vetoable– Grape’s own @Grab


@Immutable

• To properly implement immutable classes– No mutations — state musn’t change– Private final fields– Defensive copying of mutable components– Proper equals() / hashCode() / toString()

for comparisons or fas keys in maps

@Immutable 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


Grab a grape!

• Simple distribution and sharing of Groovy scripts• Dependencies stored locally

– Can even use your own local 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()}


Metaprogramming additions (1/2)

• ExpandoMetaClass DSL– factoring EMC changes

Number.metaClass { multiply { Amount amount ‐> amount.times(delegate) } div { Amount amount ‐> amount.inverse().times(delegate)

}}


Metaprogramming additions (2/2)

• Runtime mixins

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!"


JMX Builder

• A DSL for handling JMX – in addition of Groovy MBean

// Create a connector serverdef jmx = new JmxBuilder()jmx.connectorServer(port:9000).start()

// Create a connector clientjmx.connectorClient(port:9000).connect()

//Export a beanjmx.export { bean new MyService() }

// Defining a timerjmx.timer(name: "jmx.builder:type=Timer",

event: "heartbeat", period: "1s").start()

// JMX listenerjmx.listener(event: "someEvent", from: "bean",

call: { evt ‐> /* do something */ })


into the Present...jeudi 21 octobre 2010

Big highlights of Groovy 1.7

• Anonymous Inner Classes and Nested Classes• Annotations anywhere• Grape improvements• Power Asserts• AST Viewer• AST Builder• Customize the Groovy Truth!• Rewrite of the GroovyScriptEngine• Groovy Console improvements• SQL support refinements


AIC and NC

• Anonymous Inner Classes and Nested Classes


AIC and NC

• Anonymous Inner Classes and Nested Classes

For Java

copy’n paste

compatibility

sake :-)


Annonymous Inner Classes

boolean called = false

Timer timer = new Timer()

timer.schedule(new TimerTask() {

void run() {

called = true

}}, 0)

sleep 100assert called


Annonymous Inner Classes

boolean called = false

Timer timer = new Timer()

timer.schedule(new TimerTask() {

void run() {

called = true

}}, 0)

sleep 100assert called

{ called = true } as TimerTask


Nested Classes

class Environment { static class Production extends Environment {}

static class Development extends Environment {}

}

new Environment.Production()


Anotations anywhere

• You can now put annotations– on imports– on packages– on variable declarations

• Examples with @Grab following...


Grape improvements (1/4)

• @Grab on import

@Grab(group = 'net.sf.json‐lib',

module = 'json‐lib', version = '2.3', classifier = 'jdk15')import net.sf.json.groovy.*

assert new JsonSlurper().parseText(

new JsonGroovyBuilder().json {

book(title: "Groovy in Action",

author: "Dierk König et al")

}.toString()).book.title == "Groovy in Action"



• Shorter module / artifact / version parameter– Example of an annotation on a variable declaration

@Grab('net.sf.json‐lib:json‐lib:2.3:jdk15')

def builder = new net.sf.json.groovy.JsonGroovyBuilder()

def books = builder.books { book(title: "Groovy in Action", author: "Dierk Koenig")

}assert books.toString() == '{"books":{"book":{"title":"Groovy in Action",' +

'"author":"Dierk Koenig"}}}'



• Groovy 1.7 introduced Grab resolver– For when you need to specify a specific repository

for a given dependency

@GrabResolver( name = 'restlet.org', root = 'http://maven.restlet.org')

@Grab('org.restlet:org.restlet:1.1.6')

import org.restlet.Restlet


http://maven.restlet.org/












• Groovy 1.7.5 even further shrinks the grab resolver definition:

27

@GrabResolver('http://maven.restlet.org')

@Grab('org.restlet:org.restlet:1.1.6')

import org.restlet.Restlet













Power Asserts (1/2)

• Much better assert statement!– Invented and developed in the Spock framework

• Given this script...

def energy = 7200 * 10**15 + 1def mass = 80def celerity = 300000000

assert energy == mass * celerity ** 2


Power Asserts (2/2)

• You’ll get a more comprehensible output


Easier AST Transformations

• AST Transformations are a very powerful feature• But are still rather hard to develop

– Need to know the AST API closely

• To help with authoring your own transformations, we’ve introduced– the AST Viewer in the Groovy Console– the AST Builder


AST Viewer


AST Builder

// Ability to build AST parts

// ‐‐> from a Stringnew AstBuilder().buildFromString(''' "Hello" '''

)

// ‐‐> from codenew AstBuilder().buildFromCode { "Hello" }

// ‐‐> from a specification

List<ASTNode> nodes = new AstBuilder().buildFromSpec {

block { returnStatement {

constant "Hello"

} }}


Customize the Groovy Truth!

• Ability to customize the truth by implementing a boolean asBoolean() method

class Predicate { boolean value boolean asBoolean() { value }

}

def truePred = new Predicate(value: true)

def falsePred = new Predicate(value: false)

assert truePred && !falsePred


SQL support refinements

// batch statementssql.withBatch { stmt ‐>

["Paul", "Jochen", "Guillaume"].each { name ‐>

stmt.addBatch "insert into PERSON (name) values ($name)"

}}

// transaction supportdef persons = sql.dataSet("person")

sql.withTransaction { persons.add name: "Paul" persons.add name: "Jochen"

persons.add name: "Guillaume"

persons.add name: "Roshan"

}


Groovy 1.7.x changes

• Since Groovy 1.7.0, Groovy 1.7.1, 1.7.2, 1.7.3, 1.7.4 and 1.7.5 have been released already!

• Here’s what’s new!


Map improvements

// map auto‐vificationdef m = [:].withDefault { key ‐> "Default" }

assert m['z'] == "Default"

assert m['a'] == "Default"

// default sortm.sort()

// sort with a comparatorm.sort({ a, b ‐> a <=> b } as Comparator)


XML back to String

• Ability to retrieve the XML string from a node from an XmlSlurper GPathResult

def xml = """<books> <book isbn="12345">Groovy in Action</book>

</books>"""def root = new XmlSlurper().parseText(xml)

def someNode = root.bookdef builder = new StreamingMarkupBuilder()

assert builder.bindNode(someNode).toString() ==

"<book isbn='12345'>Groovy in Action</book>"


Currying improvements

// right curryingdef divide = { a, b ‐> a / b }

def halver = divide.rcurry(2)

assert halver(8) == 4 // currying n‐th parameterdef joinWithSeparator = { one, sep, two ‐>

one + sep + two}def joinWithComma = joinWithSeparator.ncurry(1, ', ')

assert joinWithComma('a', 'b') == 'a, b'


New String methods

println """ def method() { return 'bar' }""".stripIndent()

println """ |def method() { | return 'bar' |}""".stripMargin('|')

// string "translation" (UNIX tr)

assert 'hello'.tr('z‐a', 'Z‐A') == 'HELLO'

assert 'Hello World!'.tr('a‐z', 'A') == 'HAAAA WAAAA!'

assert 'Hello World!'.tr('lloo', '1234') == 'He224 W4r2d!'

// capitalize the first letter

assert 'h'.capitalize() == 'H'

assert 'hello'.capitalize() == 'Hello'

assert 'hello world'.capitalize() == 'Hello world'

// tab/space (un)expansion (UNIX expand command)

assert '1234567\t8\t '.expand() == '1234567 8 '

assert ' x '.unexpand() == ' x\t '


...and beyond!jeudi 21 octobre 2010

Groovy 1.8 & beyond

• Still subject to discussion• Always evolving roadmap• Things may change!


What’s cooking?jeudi 21 octobre 2010

What we’re working on

• More runtime performance improvements• Closures

– closure annotation parameters– closure composition– closure memoization

• New AST transformations• Gradle build• Modularizing Groovy• Align with JDK 7 / Java 7 / Project Coin• Enhanced DSL support• AST Templates


Closure annotation parameters

• Groovy 1.5 brought Java 5 annotations• What if... we could go beyond what Java offered?

– In 1.7, we can put annotations on packages, imports and variable declarations

– But annotations are still limited in terms of parameters they allow

• Here comes closure annotation parameters!– Groovy 1.8 will give us the ability to access annotation with

closure parameters at runtime


GContracts

• Closures are already allowed in the Groovy 1.7 Antlr grammar– André Steingreß created GContracts,

a «design by contract» module

// a class invariant@Invariant({ name.size() > 0 && age > ageLimit() })

// a method pre‐condition@Requires({ message != null }) // a method post‐condition@Ensures({ returnResult % 2 == 0 })


Closure composition

• Functional flavor!

46

def plus2 = { it + 2 }def times3 = { it * 3 } def composed1 = plus2 << times3assert composed1(3) == 11assert composed1(4) == plus2(times3(4))

def composed2 = times3 << plus2assert composed2(3) == 15assert composed2(5) == times3(plus2(5))

// reverse compositionassert composed1(3) == (times3 >> plus2)(3)


Closure memoization

• Memoization: remember the outcome of previous (ideally side-effect free) invocations

47

def c = { a, b ‐> sleep 1000; a + b }.memoize()

assert c(1, 2) == 3 // after 1000ms

assert c(1, 2) == 3 // return immediately

// other forms:// at least 10 invocations cached

def cAtLeast = { ... }.memoizeAtLeast(10)

// at most 10 invocations cacheddef cAtMost = { ... }.memoizeAtMost(10)

// between 10 and 20 invocations cached

def cAtLeast = { ... }.memoizeBetween(10, 20)


New AST Transformations

• Many new transformations coming up for removing even more boiler plate code– @Log, inject a logger in your classes– @Field, creates a field in your scripts– @PackageScope improvements (methods & fields)– @Synchronized, providing safer synchronization semantics– @InheritConstructor, ex. when extending Exception– @IndexedProperties, JavaBeans indexed property support– @AutoClone, automatic cloning of your beans– @AutoExternalizable, automatic externalization of your beans– @Canonical, adding equals, hashCode, toString– @EqualsAndHashCode, only adding equals and hashCode– @ToString, only adding toString– @TupleConstructor, for adding a tuple constructor




More adhoc build

More modular Groovy

More from Hans!


More modular build

• «Not everybody needs everything!» ™

• A lighter Groovy-core– what’s in groovy-all?

• Modules– test, jmx, swing, xml, sql, web, template– integration (bsf, jsr-223)– tools (groovydoc, groovyc, shell, console, java2groovy)


Java 7 / 8 / Project Coin

• JSR-292 InvokeDynamic

• Simple Closures (8)

• Proposals from Project Coin– Strings in switch (7)– Automatic Resource Management (7)– Improved generics type inference (diamond <>) (7)– Simplified varargs method invocation (7)– Better integral literals (7)– Language support for collections (8?)






















Improved DSL support

• GEP-3: an extended command expression DSL– Groovy Extension Proposal #3

• Command expressions– basically top-level statements without parens– combine named and non-named arguments in the mix

• for nicer Domain-Specific Languages–(methodName arguments )*


Before GEP-3

• The idea: extend command-expressions, beyond top-level statements, for chained method calls

• Before

send("Hello").to("Graeme")

check(that: margherita).tastes(good)

sell(100.shares).of(MSFT)

take(2.pills).of(chloroquinine).after(6.hours)

wait(10.minutes).and(execute { })

blend(red, green).of(acrylic)


With GEP-3


• After

send "Hello" to "Graeme"

check that: margherita tastes good

sell 100.shares of MSFT

take 2.pills of chloroquinine after 6.hours

wait 10.minutes and execute { }

blend red, green of acrylic


With GEP-3


• After

send "Hello" to "Graeme"

check that: margherita tastes good

sell 100.shares of MSFT

take 2.pills of chloroquinine after 6.hours

wait 10.minutes and execute { }

blend red, green of acrylic

Less parens& commas



Summary


Summary (1/2)

• No need to wait for Java 7, 8, 9...– closures, properties, interpolated strings, extended annotations,

metaprogramming, [YOU NAME IT]...


Summary (1/2)

• No need to wait for Java 7, 8, 9...– closures, properties, interpolated strings, extended annotations,

metaprogramming, [YOU NAME IT]...

Groovy’s still

innovative

since 2003!


Summary (2/2)

• But it’s more than just a language, it’s a very rich and active ecosystem!– Grails, Griffon, Gradle, GPars, Spock, Gaelyk...



Q&A


Thanks for your attention!

Guillaume Laforge

Head of Groovy Development

Email: [email protected]

Twitter: @glaforge

• References:• http://gaelyk.appspot.com/• http://groovy.codehaus.org/• http://code.google.com/appengine/


mailto:[email protected]















http://gaelyk.appspot.com

http://gaelyk.appspot.com

http://groovy.codehaus.org

http://groovy.codehaus.org

http://code.google.com/appengine/

http://code.google.com/appengine/

Images used in this presentation

House / past: http://www.flickr.com/photos/jasonepowell/3680030831/sizes/o/Present clock: http://www.flickr.com/photos/38629278@N04/3784344944/sizes/o/Future: http://www.flickr.com/photos/befuddledsenses/2904000882/sizes/l/Cooking: http://www.flickr.com/photos/eole/449958332/sizes/l/Puzzle: http://www.everystockphoto.com/photo.php?imageId=263521Light bulb: https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.pngSpeed limit : http://www.morguefile.com/archive/display/18492Warehouse : http://www.morguefile.com/archive/display/85628Check mark: http://www.lnl.infn.it/~epics/WikiDumps/localhost/600px-symbol_ok.svg.png


http://www.flickr.com/photos/jasonepowell/3680030831/sizes/o/

http://www.flickr.com/photos/jasonepowell/3680030831/sizes/o/

http://www.flickr.com/photos/38629278@N04/3784344944/sizes/o/

http://www.flickr.com/photos/38629278@N04/3784344944/sizes/o/

http://www.flickr.com/photos/befuddledsenses/2904000882/sizes/l/

http://www.flickr.com/photos/befuddledsenses/2904000882/sizes/l/

http://www.flickr.com/photos/eole/449958332/sizes/l/

http://www.flickr.com/photos/eole/449958332/sizes/l/

http://www.everystockphoto.com/photo.php?imageId=263521

http://www.everystockphoto.com/photo.php?imageId=263521

https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.png

https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.png

http://www.morguefile.com/archive/display/18492




http://www.lnl.infn.it/~epics/WikiDumps/localhost/600px-symbol_ok.svg.png

http://www.lnl.infn.it/~epics/WikiDumps/localhost/600px-symbol_ok.svg.png

Technology

Groovy to infinity and beyond - SpringOne2GX - 2010 - Guillaume Laforge