Better DSL Support for Groovy-Eclipse

What’s new in Groovy & Grails Support?
DSL Support in Groovy-Eclipse
Andrew Eisenberg, SpringSource Tools Team

© 2011 SpringSource, A division of VMware. All rights reserved

What’s new in Groovy & Grails Support?

Part 1


New Groovy-Eclipse Support in 2.5.0

  DSL Descriptors (discussed later)
  Groovy 1.8
  Parameter guessing content assist
  Script outline view
  Distinguish read vs. write access in search
  Conditional breakpoints in Groovy files (STS only)

3

New Grails tooling support in STS 2.7.0.M1

  Service field content assist
  Groovy search results in GSPs

4

Gradle support in STS

Part 1.5


First cut at Gradle support now available in STS

  Demoed this morning in the Gradle talk
  Yay!

6

DSL Support in Groovy-Eclipse

Part 2


A DSL for distance calculations

3.m + 2.yd + 2.mi - 1.km
In the Groovy editor:

Uh oh!

Can we do better???
9

The Solution:
DSL Descriptors (DSLDs)

10

DSL Descriptors

  Teach the IDE about DSLs through scripting

CONFIDENTIAL 11

DSL Descriptors

  In English:
•  “Any subtype of Number should have the following properties: m, yd, mi, km”
  In DSLD:
•  “Any subtype of Number”:
currentType( subType( Number ) )!
•  “…the following properties…”:
[ “m”, “yd”, “cm”, “mi”, “km” ].each {!
property name:it, type:"Distance”!
}!

3.m + 2.yd + 2.mi - 1.km

12

Let’s see that

  Ex 1: Distances

13

Anatomy of a DSLD file

14

DSLD and the Inferencing Engine
  Hooks into Groovy-Eclipse’s type inferencing engine
•  Visit each expression AST node
•  Determine type using previous expression
•  Move to next expression
  DSLD operates on Groovy AST Expression nodes
•  Exposes Groovy AST nodes and uses Groovy API
  In the background, while typing (reconciling)
org.codehaus.groovy.ast.expr.Expression!

15

Pointcuts and Contribution blocks
  Pointcuts:
•  Where to do it.
•  What is the current expression?
•  Declaring type? class Other {!
•  Enclosing class? def x!
}!
  Contribution blocks: class Foo {!
•  What to do def method() {!
•  “Add” method new Other().x!
•  “Add” property }!
}!
•  (not at runtime, in the editor only)

16

What goes in a Contribution Block?

  property : “adds” a property (…).accept {!
•  arguments property name: “myName”!
•  name: “blarb” method name: “getMyName”!
}!
•  type: “java.lang.String”
•  declaringType :”com.foo.Frumble”
•  isStatic: false
•  doc: “Some html”
•  provider: “My DSL”
  method : “adds” a method
•  all arguments above, and
•  params: [firstName:“java.lang.String”, lastName:“java.lang.String”]
•  useNamedArgs: true

  name is required, others optional

17

Pointcuts

  currentType() : Matches on the current declaring type
  enclosingClass() : Matches on the enclosing class
  currentType(“com.bar.Foo”)
  methods(“run”)
  annotatedBy(“org.junit.runner.RunWith”)
  enclosingClass(
annotatedBy(“org.junit.runner.RunWith”) ) &
currentType(methods(“run”) )

18

Where does this pointcut match? What does it add?
(enclosingClass(annotatedBy(“org.junit.runner.RunWith”)) &  
currentType(methods(“run”))).accept { property name:”blarb” }!

Looking for an expression that:
@RunWith(Sumthin) !
class Foo {!
def someTest() {! enclosed by
@RunWith
print “Hello”!
def x = new MyRunner()!
x.blarb! has run method
}!
blarb
}!
class MyRunner { def run() {…} }!

19

Wait…isn’t this Aspect-Oriented Programming?

  Pointcut
•  Intentionally borrowed from AOP
  AspectJ: pointcuts and advice
•  operates on Java instructions at runtime
class Foo {!
  DSLD: pointcuts and contribution blocks def x = {!
•  operates on AST def i = 0!
org.codehaus.groovy.ast.expr.*!
  Join Point Model i++!
}!
•  Join points (e.g., instructions, expressions)
}!
•  Mechanism for quantifying join points (e.g., pointcuts)
•  Means of affect at a join point (e.g., advice,
contribution blocks)

20

Other things to help with DSLDs

21

New DSLD Wizard

  File  New  Groovy DSL Descriptor

22

DSLD Preferences Page

23

Groovy Event Console

  Keep this open while implementing DSLDs:
•  Shows exceptions
•  Pointcuts
•  Matches

  Find the Console here:

24

Groovy AST Viewer

  Exploration of AST of current Groovy file

25

Basic Script
Ex 2: Using the DSLD wizard

27

Meta DSL
Ex 3: DSLD script for editing DSLDs

28

AST Transforms
Ex 3: Standard AST Transforms

29

SwingBuilder
Ex 4: Long script, but simple to understand

30

Grails Constraints DSL
Ex 5: encapsulate Grails domain knowledge in a script

31

Criteria Queries
Ex 6: simple script, large effect

32

Griffon
Ex 7: from last night

33

DSLD is not complete

  Guided by user feedback
  Collaboration with library developers
•  Grails, Gaelyk, Griffon, etc.
  Release standard DSLDs (AST Transforms, Builders, etc.)
•  With Groovy-Eclipse?
•  With Groovy core?
  More pointcuts
•  What do users need that isn’t implemented?
•  regex(), instanceof(), superType(), enclosingEnum(), etc.
  What about IntelliJ’s GDSL?

35

Thanks!

  More information:
•  Google: groovy eclipse dsld
  Full documentation on Codehaus.org:
•  http://docs.codehaus.org/display/GROOVY/DSL+Descriptors+for+Groovy-Eclipse
  Install from update site:
•  http://dist.codehaus.org/groovy/distributions/greclipse/snapshot/e3.6/
  Mailing list:
•  eclipse-plugin-users@codehaus.org
  Or chat with me whenever

36

Better DSL Support for Groovy-Eclipse

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