Groovy in 2014 and beyond -- Groovy Grails eXchange 2014

As usual, Guillaume Laforge will go through the latest developments of the Groovy programming language and will update you with what's going on, what's to come, and beyond the language itself.

Transcript

1. @glaforge
   #groovylang
   Groovy
   in 2014
   & beyond
   Guillaume Laforge
   Groovy project manager
   

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2. #groovylang @glaforge
   Stay up-to-date
   Groovy Weekly newsletter (every Tuesday) 

   http://beta.groovy-lang.org/groovy-weekly.html
   2
   

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3. #groovylang @glaforge
   The Groovy roadmap
   3
   2015
   2014
   2013
   Groovy 2.3
   Groovy 2.4
   Groovy 2.2
   Groovy 2.5
   Groovy 3.0 ?
   

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4. @glaforge
   #groovylang
   Groovy 2.3
   

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5. @glaforge
   #groovylang
   JDK 8 support
   

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6. #groovylang @glaforge
   JDK 8 support — closures vs lambdas
   6
   IntStream.range(1,  100).forEach(s  -­‐>      
                                            System.out.println(s));  
   Files.lines(Paths.get('README.adoc'))  
            .map(it  -­‐>  it.toUpperCase())  
            .forEach(it  -­‐>  System.out.println(it));
   

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7. #groovylang @glaforge
   JDK 8 support — closures vs lambdas
   6
   IntStream.range(1,  100).forEach(s  -­‐>      
                                            System.out.println(s));  
   Files.lines(Paths.get('README.adoc'))  
            .map(it  -­‐>  it.toUpperCase())  
            .forEach(it  -­‐>  System.out.println(it));
   IntStream.range(1,  100).forEach  {  println  it  }  
   Files.lines(Paths.get('README.adoc'))  
            .map  {  it.toUpperCase()  }  
            .forEach  {  println  it  }
   

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8. #groovylang @glaforge
   JDK 8 support — closures vs lambdas
   6
   IntStream.range(1,  100).forEach(s  -­‐>      
                                            System.out.println(s));  
   Files.lines(Paths.get('README.adoc'))  
            .map(it  -­‐>  it.toUpperCase())  
            .forEach(it  -­‐>  System.out.println(it));
   IntStream.range(1,  100).forEach  {  println  it  }  
   Files.lines(Paths.get('README.adoc'))  
            .map  {  it.toUpperCase()  }  
            .forEach  {  println  it  }
   Use Groovy closures
   wherever you pass
   lambdas in Java 8
   

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9. @glaforge
   #groovylang
   Traits
   

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10. #groovylang @glaforge
    Traits
    • Like interfaces, but with method bodies
    • similar to Java 8 interface default methods
    • Elegant way to compose behavior
    • multiple inheritance without the « diamond » problem
    • Traits can also be stateful
    • traits can have properties like normal classes
    • Compatible with static typing and static compilation
    • class methods from traits also visible from Java classes
    • Also possible to implement traits at runtime
    8
    

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11. #groovylang @glaforge
    Traits: a simple example
    9
    trait  FlyingAbility  {  
           String  fly()  {  "I'm  flying!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird()  
    assert  b.fly()  ==  "I'm  flying!"
    

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12. #groovylang @glaforge
    Traits: a simple example
    9
    trait  FlyingAbility  {  
           String  fly()  {  "I'm  flying!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird()  
    assert  b.fly()  ==  "I'm  flying!"
    « trait », a new keyword
    for a new concept
    

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13. #groovylang @glaforge
    Traits: a simple example
    9
    trait  FlyingAbility  {  
           String  fly()  {  "I'm  flying!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird()  
    assert  b.fly()  ==  "I'm  flying!"
    a class 

    « implements »

    a trait
    

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14. #groovylang @glaforge
    Traits: a simple example
    9
    trait  FlyingAbility  {  
           String  fly()  {  "I'm  flying!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird()  
    assert  b.fly()  ==  "I'm  flying!"
    the fly() method from
    the trait is available
    

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15. #groovylang @glaforge
    Traits: a simple example
    9
    trait  FlyingAbility  {  
           String  fly()  {  "I'm  flying!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird()  
    assert  b.fly()  ==  "I'm  flying!"
    

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16. #groovylang @glaforge
    Traits: stateful
    10
    trait  Named  {  
           String  name  
    }  
    class  Bird  implements  Named  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'
    

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17. #groovylang @glaforge
    Traits: stateful
    10
    trait  Named  {  
           String  name  
    }  
    class  Bird  implements  Named  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'
    a Groovy property
    

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18. #groovylang @glaforge
    Traits: stateful
    10
    trait  Named  {  
           String  name  
    }  
    class  Bird  implements  Named  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'
    implement the trait
    

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19. #groovylang @glaforge
    Traits: stateful
    10
    trait  Named  {  
           String  name  
    }  
    class  Bird  implements  Named  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'
    Groovy named
    argument constructor
    

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20. #groovylang @glaforge
    Traits: stateful
    10
    trait  Named  {  
           String  name  
    }  
    class  Bird  implements  Named  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'
    access the property
    

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21. #groovylang @glaforge
    Traits: stateful
    10
    trait  Named  {  
           String  name  
    }  
    class  Bird  implements  Named  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'
    

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22. #groovylang @glaforge
    Traits: inheritance
    11
    trait  Named  {  String  name  }  
    trait  FlyingAbility  extends  Named  {  
           String  fly()  {  "I'm  a  flying  ${name}!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'  
    assert  b.fly()  ==  "I'm  a  flying  Colibri!"
    

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23. #groovylang @glaforge
    Traits: inheritance
    11
    trait  Named  {  String  name  }  
    trait  FlyingAbility  extends  Named  {  
           String  fly()  {  "I'm  a  flying  ${name}!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'  
    assert  b.fly()  ==  "I'm  a  flying  Colibri!"
    extend the Named trait
    

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24. #groovylang @glaforge
    Traits: inheritance
    11
    trait  Named  {  String  name  }  
    trait  FlyingAbility  extends  Named  {  
           String  fly()  {  "I'm  a  flying  ${name}!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'  
    assert  b.fly()  ==  "I'm  a  flying  Colibri!"
    access the name property
    

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25. #groovylang @glaforge
    Traits: inheritance
    11
    trait  Named  {  String  name  }  
    trait  FlyingAbility  extends  Named  {  
           String  fly()  {  "I'm  a  flying  ${name}!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'  
    assert  b.fly()  ==  "I'm  a  flying  Colibri!"
    implement the
    composite trait
    

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26. #groovylang @glaforge
    Traits: inheritance
    11
    trait  Named  {  String  name  }  
    trait  FlyingAbility  extends  Named  {  
           String  fly()  {  "I'm  a  flying  ${name}!"  }  
    }  
    class  Bird  implements  FlyingAbility  {}  
    def  b  =  new  Bird(name:  'Colibri')  
    assert  b.name  ==  'Colibri'  
    assert  b.fly()  ==  "I'm  a  flying  Colibri!"
    

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27. #groovylang @glaforge
    Traits: what about conflicts?
    12
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  KiteSurfer,  WebSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'web'
    

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28. #groovylang @glaforge
    Traits: what about conflicts?
    12
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  KiteSurfer,  WebSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'web'
    two surf() methods
    

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29. #groovylang @glaforge
    Traits: what about conflicts?
    12
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  KiteSurfer,  WebSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'web'
    

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30. #groovylang @glaforge
    Traits: what about conflicts?
    12
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  KiteSurfer,  WebSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'web'
    extending a class and
    implementing the two traits
    

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31. #groovylang @glaforge
    Traits: what about conflicts?
    12
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  KiteSurfer,  WebSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'web'
    

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32. #groovylang @glaforge
    Traits: what about conflicts?
    12
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  KiteSurfer,  WebSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'web'
    last declared trait wins!
    

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33. #groovylang @glaforge
    Traits: what about conflicts?
    12
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  KiteSurfer,  WebSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'web'
    

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34. #groovylang @glaforge
    Traits: what about conflicts?
    13
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  WebSurfer,  KiteSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'kite'
    

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35. #groovylang @glaforge
    Traits: what about conflicts?
    13
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  WebSurfer,  KiteSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'kite'
    reverse the order!
    

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36. #groovylang @glaforge
    Traits: what about conflicts?
    13
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  WebSurfer,  KiteSurfer  {}  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'kite'
    

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37. #groovylang @glaforge
    Traits: what about conflicts?
    14
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  WebSurfer,  KiteSurfer  {  
           String  surf()  {  KiteSurfer.super.surf()  }  
    }  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'kite'
    

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38. #groovylang @glaforge
    Traits: what about conflicts?
    14
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  WebSurfer,  KiteSurfer  {  
           String  surf()  {  KiteSurfer.super.surf()  }  
    }  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'kite'
    Be explicit!
    Override surf() 

    & use ‘super’
    

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39. #groovylang @glaforge
    Traits: what about conflicts?
    14
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  WebSurfer,  KiteSurfer  {  
           String  surf()  {  KiteSurfer.super.surf()  }  
    }  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'kite'
    Your class method takes
    precedence over the traits
    

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40. #groovylang @glaforge
    Traits: what about conflicts?
    14
    trait  KiteSurfer  {  String  surf()  {  'kite'  }  }  
    trait  WebSurfer    {  String  surf()  {    'web'  }  }  
    class  Person  {  String  name  }  
    class  Hipster  extends  Person  
                         implements  WebSurfer,  KiteSurfer  {  
           String  surf()  {  KiteSurfer.super.surf()  }  
    }  
    def  h  =  new  Hipster()  
    assert  h.surf()  ==  'kite'
    

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41. #groovylang @glaforge
    Traits: runtime implementation
    15
    trait  Named  {  
           String  name  
    }  
    class  Animal  {}  
    class  NamedAnimal  implements  Named  {}  
    def  na  =  new  NamedAnimal(name:  'Felix')  
    assert  na.name  ==  'Felix'
    

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42. #groovylang @glaforge
    Traits: runtime implementation
    15
    trait  Named  {  
           String  name  
    }  
    class  Animal  {}  
    class  NamedAnimal  implements  Named  {}  
    def  na  =  new  NamedAnimal(name:  'Felix')  
    assert  na.name  ==  'Felix'
    Somewhat artificial to have to
    create an intermediary class to
    get named animals
    

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43. #groovylang @glaforge
    Traits: runtime implementation
    15
    trait  Named  {  
           String  name  
    }  
    class  Animal  {}  
    class  NamedAnimal  implements  Named  {}  
    def  na  =  new  NamedAnimal(name:  'Felix')  
    assert  na.name  ==  'Felix'
    

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44. #groovylang @glaforge
    Traits: runtime implementation
    16
    trait  Named  {  
           String  name  
    }  
    class  Animal  {}  
    def  na  =  new  Animal()  as  Named  
    na.name  =  'Felix'  
    assert  na.name  ==  'Felix'
    

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45. #groovylang @glaforge
    Traits: runtime implementation
    16
    trait  Named  {  
           String  name  
    }  
    class  Animal  {}  
    def  na  =  new  Animal()  as  Named  
    na.name  =  'Felix'  
    assert  na.name  ==  'Felix'
    Runtime trait, 

    with Groovy’s usual
    coercion mechanism
    

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46. #groovylang @glaforge
    Traits: runtime implementation
    16
    trait  Named  {  
           String  name  
    }  
    class  Animal  {}  
    def  na  =  new  Animal()  as  Named  
    na.name  =  'Felix'  
    assert  na.name  ==  'Felix'
    

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47. #groovylang @glaforge
    Traits: runtime implementation
    17
    trait  Named  {  String  name  }  
    trait  Quacks  {  
           String  quack()  {  'Quack!'  }  
    }  
    class  Animal  {}  
    def  na  =  new  Animal().withTraits  Named,  Quacks  
    na.name  =  'Daffy'  
    assert  na.name  ==  'Daffy'  
    assert  na.quack()  ==  'Quack!'
    

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48. #groovylang @glaforge
    Traits: runtime implementation
    17
    trait  Named  {  String  name  }  
    trait  Quacks  {  
           String  quack()  {  'Quack!'  }  
    }  
    class  Animal  {}  
    def  na  =  new  Animal().withTraits  Named,  Quacks  
    na.name  =  'Daffy'  
    assert  na.name  ==  'Daffy'  
    assert  na.quack()  ==  'Quack!'
    Implement several traits at
    once, at runtime
    

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49. #groovylang @glaforge
    Traits: runtime implementation
    17
    trait  Named  {  String  name  }  
    trait  Quacks  {  
           String  quack()  {  'Quack!'  }  
    }  
    class  Animal  {}  
    def  na  =  new  Animal().withTraits  Named,  Quacks  
    na.name  =  'Daffy'  
    assert  na.name  ==  'Daffy'  
    assert  na.quack()  ==  'Quack!'
    

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50. @glaforge
    #groovylang
    AST transforms
    

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51. #groovylang @glaforge
    New: @TailRecursive
    19
    import  groovy.transform.TailRecursive  
    @TailRecursive  
    def  fact(BigInteger  n,  accu  =  1G)  {  
           if  (n  <  2)  accu  
           else  fact(n  -­‐  1,  n  *  accu)  
    }  
    assert  fact(1000)  >  10e2566
    

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52. #groovylang @glaforge
    New: @TailRecursive
    19
    import  groovy.transform.TailRecursive  
    @TailRecursive  
    def  fact(BigInteger  n,  accu  =  1G)  {  
           if  (n  <  2)  accu  
           else  fact(n  -­‐  1,  n  *  accu)  
    }  
    assert  fact(1000)  >  10e2566
    Rewrites tail recursive
    friendly function serially
    

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53. #groovylang @glaforge
    New: @TailRecursive
    19
    import  groovy.transform.TailRecursive  
    @TailRecursive  
    def  fact(BigInteger  n,  accu  =  1G)  {  
           if  (n  <  2)  accu  
           else  fact(n  -­‐  1,  n  *  accu)  
    }  
    assert  fact(1000)  >  10e2566
    Doesn’t blow up with a
    stack overflow error
    

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54. #groovylang @glaforge
    New: @TailRecursive
    19
    import  groovy.transform.TailRecursive  
    @TailRecursive  
    def  fact(BigInteger  n,  accu  =  1G)  {  
           if  (n  <  2)  accu  
           else  fact(n  -­‐  1,  n  *  accu)  
    }  
    assert  fact(1000)  >  10e2566
    Downside of tail recursion is 

    you might have to rewrite 

    your algo to be tailrec friendly
    

    View Slide

55. #groovylang @glaforge
    New: @TailRecursive
    19
    import  groovy.transform.TailRecursive  
    @TailRecursive  
    def  fact(BigInteger  n,  accu  =  1G)  {  
           if  (n  <  2)  accu  
           else  fact(n  -­‐  1,  n  *  accu)  
    }  
    assert  fact(1000)  >  10e2566
    

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56. #groovylang @glaforge
    New: @Sortable
    20
    import  groovy.transform.*  
    @Sortable  
    class  Person  {  
           String  lastName  
           String  firstName  
           int  age  
    }
    

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57. #groovylang @glaforge
    New: @Sortable
    20
    import  groovy.transform.*  
    @Sortable  
    class  Person  {  
           String  lastName  
           String  firstName  
           int  age  
    }
    Makes the class Comparable
    by multiple Comparators
    

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58. #groovylang @glaforge
    New: @Sortable
    20
    import  groovy.transform.*  
    @Sortable  
    class  Person  {  
           String  lastName  
           String  firstName  
           int  age  
    }
    First compare by lastName,
    then by firstName, etc.
    

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59. #groovylang @glaforge
    New: @Sortable
    20
    import  groovy.transform.*  
    @Sortable  
    class  Person  {  
           String  lastName  
           String  firstName  
           int  age  
    }
    You can also specify
    ‘includes’ / ‘excludes’
    properties
    

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60. #groovylang @glaforge
    New: @Sortable
    20
    import  groovy.transform.*  
    @Sortable  
    class  Person  {  
           String  lastName  
           String  firstName  
           int  age  
    }
    

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61. #groovylang @glaforge
    New: @Builder for fluent APIs
    21
    import  groovy.transform.builder.Builder

    

    @Builder

    class  Person  {

       String  firstName

       String  lastName

       int  age

    }
    

    View Slide

62. #groovylang @glaforge
    New: @Builder for fluent APIs
    21
    import  groovy.transform.builder.Builder

    

    @Builder

    class  Person  {

       String  firstName

       String  lastName

       int  age

    }
    def  person  =  Person.builder()

                   .firstName("Robert")

                   .lastName("Lewandowski")

                   .age(21)

                   .build()
    

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63. #groovylang @glaforge
    New: @Builder for fluent APIs
    21
    import  groovy.transform.builder.Builder

    

    @Builder

    class  Person  {

       String  firstName

       String  lastName

       int  age

    }
    def  person  =  Person.builder()

                   .firstName("Robert")

                   .lastName("Lewandowski")

                   .age(21)

                   .build()
    Different implementation
    strategies available
    

    View Slide

64. #groovylang @glaforge
    New: @Builder for fluent APIs
    21
    import  groovy.transform.builder.Builder

    

    @Builder

    class  Person  {

       String  firstName

       String  lastName

       int  age

    }
    def  person  =  Person.builder()

                   .firstName("Robert")

                   .lastName("Lewandowski")

                   .age(21)

                   .build()
    

    View Slide

65. #groovylang @glaforge
    @BaseScript improvements
    22
    abstract  class  CustomBase  extends  Script  {  
           int  meaningOfLife  =  42  
    }
    @BaseScript(CustomBase)  
    import  groovy.transform.BaseScript  
    assert  meaningOfLife  ==  42
    

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66. #groovylang @glaforge
    @BaseScript improvements
    22
    abstract  class  CustomBase  extends  Script  {  
           int  meaningOfLife  =  42  
    }
    @BaseScript(CustomBase)  
    import  groovy.transform.BaseScript  
    assert  meaningOfLife  ==  42
    You can add your own base methods and
    properties to all compiled scripts
    

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67. #groovylang @glaforge
    @BaseScript improvements
    22
    abstract  class  CustomBase  extends  Script  {  
           int  meaningOfLife  =  42  
    }
    @BaseScript(CustomBase)  
    import  groovy.transform.BaseScript  
    assert  meaningOfLife  ==  42
    Define the base script
    class for this script
    

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68. #groovylang @glaforge
    @BaseScript improvements
    22
    abstract  class  CustomBase  extends  Script  {  
           int  meaningOfLife  =  42  
    }
    @BaseScript(CustomBase)  
    import  groovy.transform.BaseScript  
    assert  meaningOfLife  ==  42
    Ability to put the annotation on
    imports & package
    

    View Slide

69. #groovylang @glaforge
    @BaseScript improvements
    22
    abstract  class  CustomBase  extends  Script  {  
           int  meaningOfLife  =  42  
    }
    @BaseScript(CustomBase)  
    import  groovy.transform.BaseScript  
    assert  meaningOfLife  ==  42
    

    View Slide

70. #groovylang @glaforge
    @BaseScript custom abstract method
    23
    abstract  class  CustomBase  extends  Script  {  
       def  run()  {  
           before()  
           internalRun()  
           after()  
       }  
       abstract  internalRun()  
       def  before()  {  println  'before'  }  
       def  after()    {  println  'after'    }  
    }
    

    View Slide

71. #groovylang @glaforge
    @BaseScript custom abstract method
    23
    abstract  class  CustomBase  extends  Script  {  
       def  run()  {  
           before()  
           internalRun()  
           after()  
       }  
       abstract  internalRun()  
       def  before()  {  println  'before'  }  
       def  after()    {  println  'after'    }  
    }
    import  groovy.transform.BaseScript  
    @BaseScript  CustomBase  script  
    println  'Hello'
    

    View Slide

72. #groovylang @glaforge
    @BaseScript custom abstract method
    23
    abstract  class  CustomBase  extends  Script  {  
       def  run()  {  
           before()  
           internalRun()  
           after()  
       }  
       abstract  internalRun()  
       def  before()  {  println  'before'  }  
       def  after()    {  println  'after'    }  
    }
    import  groovy.transform.BaseScript  
    @BaseScript  CustomBase  script  
    println  'Hello'
    You can define your own abstract
    method for script bodies
    

    View Slide

73. #groovylang @glaforge
    @BaseScript custom abstract method
    23
    abstract  class  CustomBase  extends  Script  {  
       def  run()  {  
           before()  
           internalRun()  
           after()  
       }  
       abstract  internalRun()  
       def  before()  {  println  'before'  }  
       def  after()    {  println  'after'    }  
    }
    import  groovy.transform.BaseScript  
    @BaseScript  CustomBase  script  
    println  'Hello'
    

    View Slide

74. @glaforge
    #groovylang
    NIO2 module
    

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75. #groovylang @glaforge
    JDK 7+ NIO2 module
    • All the familiar methods on File 

    retrofitted on Path as well
    25
    path.withReader  {  Reader  r  -­‐>  ...  }  
    path.eachLine  {  String  line  -­‐>  ...  }  
    path.eachFileRecurse  {  Path  p  -­‐>  ...  }  
    path  <<  'some  content'  
    path  <<  bytes  
    path.readLines()  
    …
    

    View Slide

76. #groovylang @glaforge
    JDK 7+ NIO2 module
    • All the familiar methods on File 

    retrofitted on Path as well
    25
    path.withReader  {  Reader  r  -­‐>  ...  }  
    path.eachLine  {  String  line  -­‐>  ...  }  
    path.eachFileRecurse  {  Path  p  -­‐>  ...  }  
    path  <<  'some  content'  
    path  <<  bytes  
    path.readLines()  
    …
    Feature request to add all the
    java.nio.file.Files static utility
    methods as GDK
    

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77. #groovylang @glaforge
    JDK 7+ NIO2 module
    • All the familiar methods on File 

    retrofitted on Path as well
    25
    path.withReader  {  Reader  r  -­‐>  ...  }  
    path.eachLine  {  String  line  -­‐>  ...  }  
    path.eachFileRecurse  {  Path  p  -­‐>  ...  }  
    path  <<  'some  content'  
    path  <<  bytes  
    path.readLines()  
    …
    

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78. @glaforge
    #groovylang
    JSON
    

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79. #groovylang @glaforge
    JSON parser / builder perf. increase
    • Re-implementation of JSON support for speed & efficiency
    • parser forked off the Boon JSON project
    • serializer carefully fine-tuned
    • Article on the parsing speed improvements
    • http://rick-hightower.blogspot.fr/2014/04/groovy-and-boon-provide-fastest-json.html
    27
    

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80. #groovylang @glaforge
    JSON parser / builder perf. increase
    • Re-implementation of JSON support for speed & efficiency
    • parser forked off the Boon JSON project
    • serializer carefully fine-tuned
    • Article on the parsing speed improvements
    • http://rick-hightower.blogspot.fr/2014/04/groovy-and-boon-provide-fastest-json.html
    27
    

    View Slide

81. #groovylang @glaforge
    JSON parser / builder perf. increase
    • Re-implementation of JSON support for speed & efficiency
    • parser forked off the Boon JSON project
    • serializer carefully fine-tuned
    • Article on the parsing speed improvements
    • http://rick-hightower.blogspot.fr/2014/04/groovy-and-boon-provide-fastest-json.html
    27
    Benchmark gives 3x to 4x
    performance factor 

    over Jackson and GSON
    

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82. #groovylang @glaforge
    JSON parser / builder perf. increase
    • Re-implementation of JSON support for speed & efficiency
    • parser forked off the Boon JSON project
    • serializer carefully fine-tuned
    • Article on the parsing speed improvements
    • http://rick-hightower.blogspot.fr/2014/04/groovy-and-boon-provide-fastest-json.html
    27
    

    View Slide

83. #groovylang @glaforge
    New modes for parsing
    • Original JsonSlurper renamed to JsonSlurperClassic
    • Additional parsing modes:
    • INDEX_OVERLAY: super fast for <2MB payloads
    • using a « parsing overlay » technique
    • CHARACTER_SOURCE: for >2MB payloads
    • implemented with sliding windows over readers
    • LAX: beyond the JSON spec, nice for configuration files
    • support single quotes, / and # comments
    • CHAR_BUFFER: general purpose
    28
    

    View Slide

84. #groovylang @glaforge
    JsonSlurper for configuration files
    29
    import  groovy.json.*  
    import  static  groovy.json.JsonParserType.*  
    def  parser  =  new  JsonSlurper().setType(LAX)  
    def  conf  =  parser.parseText  '''  
           //  configuration  file  
           {  
                   //  no  quote  for  key,  single  quoted  value  
                   environment:  'production'  
                   #  pound-­‐style  comment  
                   'server':  5  
           }  
    '''  
    assert  conf.environment  ==  'production'  
    assert  conf.server  ==  5
    

    View Slide

85. #groovylang @glaforge
    JsonSlurper for configuration files
    29
    import  groovy.json.*  
    import  static  groovy.json.JsonParserType.*  
    def  parser  =  new  JsonSlurper().setType(LAX)  
    def  conf  =  parser.parseText  '''  
           //  configuration  file  
           {  
                   //  no  quote  for  key,  single  quoted  value  
                   environment:  'production'  
                   #  pound-­‐style  comment  
                   'server':  5  
           }  
    '''  
    assert  conf.environment  ==  'production'  
    assert  conf.server  ==  5
    More tolerant parser: 

    single quotes, 

    non-quoted keys, 

    // and # comments,
    missing comas
    

    View Slide

86. #groovylang @glaforge
    JsonSlurper for configuration files
    29
    import  groovy.json.*  
    import  static  groovy.json.JsonParserType.*  
    def  parser  =  new  JsonSlurper().setType(LAX)  
    def  conf  =  parser.parseText  '''  
           //  configuration  file  
           {  
                   //  no  quote  for  key,  single  quoted  value  
                   environment:  'production'  
                   #  pound-­‐style  comment  
                   'server':  5  
           }  
    '''  
    assert  conf.environment  ==  'production'  
    assert  conf.server  ==  5
    

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87. @glaforge
    #groovylang
    Markup template engine
    >
    

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88. #groovylang @glaforge
    Markup template engine
    • Based on the principles of Groovy’s « builders »
    • and particularly the MarkupBuilder class

    for generating arbitrary XML / HTML payloads
    • Compiled statically for fast template rendering
    • Internationalization aware
    • provide the desired Locale in the configuration object
    • usual suffix notation template_fr_FR.tpl
    • Custom base template class
    • ability to provide reusable methods across your templates
    31
    

    View Slide

89. #groovylang @glaforge
    Markup template engine
    • Based on the principles of Groovy’s « builders »
    • and particularly the MarkupBuilder class

    for generating arbitrary XML / HTML payloads
    • Compiled statically for fast template rendering
    • Internationalization aware
    • provide the desired Locale in the configuration object
    • usual suffix notation template_fr_FR.tpl
    • Custom base template class
    • ability to provide reusable methods across your templates
    31
    Spring Boot
    approved
    

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90. #groovylang @glaforge
    Markup template engine — the idea
    32
    cars  {  
         cars.each  {  
                 car(make:  it.make,  name:  it.name)  
         }  
    }
    

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91. #groovylang @glaforge
    Markup template engine — the idea
    32
    cars  {  
         cars.each  {  
                 car(make:  it.make,  name:  it.name)  
         }  
    }
    Your template
    

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92. #groovylang @glaforge
    Markup template engine — the idea
    32
    cars  {  
         cars.each  {  
                 car(make:  it.make,  name:  it.name)  
         }  
    }
    model = [cars: [
    new Car(make: 'Peugeot', name: '508'),
    new Car(make: 'Toyota', name: 'Prius’)
    ]]
    

    View Slide

93. #groovylang @glaforge
    Markup template engine — the idea
    32
    cars  {  
         cars.each  {  
                 car(make:  it.make,  name:  it.name)  
         }  
    }
    model = [cars: [
    new Car(make: 'Peugeot', name: '508'),
    new Car(make: 'Toyota', name: 'Prius’)
    ]]
    Feed a model into your
    template
    

    View Slide

94. #groovylang @glaforge
    Markup template engine — the idea
    32
    cars  {  
         cars.each  {  
                 car(make:  it.make,  name:  it.name)  
         }  
    }
    model = [cars: [
    new Car(make: 'Peugeot', name: '508'),
    new Car(make: 'Toyota', name: 'Prius’)
    ]]
    
    
    
    
    

    View Slide

95. #groovylang @glaforge
    Markup template engine — the idea
    32
    cars  {  
         cars.each  {  
                 car(make:  it.make,  name:  it.name)  
         }  
    }
    model = [cars: [
    new Car(make: 'Peugeot', name: '508'),
    new Car(make: 'Toyota', name: 'Prius’)
    ]]
    
    
    
    
    Generate the XML
    output
    

    View Slide

96. #groovylang @glaforge
    Markup template engine — the idea
    32
    cars  {  
         cars.each  {  
                 car(make:  it.make,  name:  it.name)  
         }  
    }
    model = [cars: [
    new Car(make: 'Peugeot', name: '508'),
    new Car(make: 'Toyota', name: 'Prius’)
    ]]
    
    
    
    
    

    View Slide

97. #groovylang @glaforge
    Markup template engine — in action
    33
    import  groovy.text.markup.*  
    def  config  =  new  TemplateConfiguration()  
    def  engine  =  new  MarkupTemplateEngine(config)  
    def  tmpl  =  engine.createTemplate('''  
           p("Hello  ${model.name}")  
    ''')  
    def  model  =  [name:  'World']  
    System.out  <<  tmpl.make(model)
    

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98. #groovylang @glaforge
    Markup template engine — includes
    34
    //  include  another  template  
    include  template:  'foo.tpl'  
           
    //  include  raw  content  
    include  unescaped:  'raw.txt'  
    //  escape  &  include  
    include  escaped:  'to_escape.txt'
    

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99. #groovylang @glaforge
    Markup template engine — static!
    • Type-checked templates available
    • use createTypeCheckedModelTemplate() 

    instead of createTemplate()
    • Advantages
    • get compilation errors
    • if a variable is not available
    • if you make mistakes in the code snippets
    • even faster templates
    35
    

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100. #groovylang @glaforge
     Markup template engine — static!
     • With typed checked model creation method
     36
     

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101. #groovylang @glaforge
     Markup template engine — static!
     • With typed checked model creation method
     36
     def  modelTypes  =  [cars:  "List"]  
     def  tmpl  =  engine.  
        createTypeCheckedModelTemplate(

                "page.tpl",  modelTypes)
     

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102. #groovylang @glaforge
     Markup template engine — static!
     • With typed checked model creation method
     36
     def  modelTypes  =  [cars:  "List"]  
     def  tmpl  =  engine.  
        createTypeCheckedModelTemplate(

                "page.tpl",  modelTypes)
     modelTypes  =  {  
            List  cars  
     }  
     cars.each  {  car  -­‐>  
            p("Car  name:  $car.name")  
     }
     

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103. #groovylang @glaforge
     Markup template engine — static!
     • With typed checked model creation method
     36
     def  modelTypes  =  [cars:  "List"]  
     def  tmpl  =  engine.  
        createTypeCheckedModelTemplate(

                "page.tpl",  modelTypes)
     modelTypes  =  {  
            List  cars  
     }  
     cars.each  {  car  -­‐>  
            p("Car  name:  $car.name")  
     }
     Works with
     createTemplate() too
     

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104. #groovylang @glaforge
     Markup template engine — static!
     • With typed checked model creation method
     36
     def  modelTypes  =  [cars:  "List"]  
     def  tmpl  =  engine.  
        createTypeCheckedModelTemplate(

                "page.tpl",  modelTypes)
     modelTypes  =  {  
            List  cars  
     }  
     cars.each  {  car  -­‐>  
            p("Car  name:  $car.name")  
     }
     

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105. @glaforge
     #groovylang
     Documentation overhaul
     

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106. #groovylang @glaforge
     GroovyDoc
     38
     

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107. #groovylang @glaforge
     GroovyDoc
     38
     

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108. #groovylang @glaforge
     GroovyDoc
     38
     

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109. #groovylang @glaforge
     Groovy GDK documentation
     39
     

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110. #groovylang @glaforge
     Groovy GDK documentation
     39
     

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111. #groovylang @glaforge
     Brand new documentation
     40
     

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112. @glaforge
     #groovylang
     Groovy 2.4
     

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113. #groovylang @glaforge
     Beta groovy-lang.org website
     42
     

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114. #groovylang @glaforge
     Beta groovy-lang.org website
     42
     

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115. #groovylang @glaforge
     Beta groovy-lang.org website
     42
     

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116. #groovylang @glaforge
     Beta groovy-lang.org website
     42
     Notice the « improve
     this doc » button!
     

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117. #groovylang @glaforge
     Android support
     • You can use Groovy to code Android apps!
     • use Groovy 2.4.0-beta-1+
     • prefer @CompileStatic
     • Two great posts to get started:
     • http://melix.github.io/blog/2014/06/grooid.html
     • http://melix.github.io/blog/2014/06/grooid2.html
     43
     

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118. #groovylang @glaforge
     New York Times — Getting Groovy with
     44
     

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119. #groovylang @glaforge
     New York Times — Getting Groovy with
     44
     http://bit.ly/nyt-groovy
     

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120. #groovylang @glaforge
     Android support
     45
     

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121. #groovylang @glaforge
     Android support
     45
     Source code available:
     https://github.com/melix/gr8confagenda
     

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122. #groovylang @glaforge
     Type constraints on traits with @SelfType
     • Only apply a trait to some child classes
     46
     class  Component  {

            void  doSomething()  {}

     }

     

     @SelfType(Component)

     trait  ComponentDecorator  {

            void  logAndDoSomething()  {

                    println  "Calling  doSomething()"

                    doSomething()

            }

     }
     

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123. #groovylang @glaforge
     StreamingTemplateEngine
     • Uses writable closures to stream the output
     • Works with templates bigger than 64K
     47
     import  groovy.text.*  
     def  eng  =  new  StreamingTemplateEngine()  
     def  tpl  =  eng.createTemplate  '''

            Hi  ${name}

     '''  
     println  tpl.make(name:  'Guillaume')
     

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124. @glaforge
     #groovylang
     Groovy 2.5
     

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125. #groovylang @glaforge
     Groovy Macros
     • Sergei Egorov wants to contribute a macro module
     • https://github.com/groovy/groovy-core/pull/470
     • Simplify creation of AST transformations
     • less boilerplate manipulating the Groovy AST API
     • more powerful and less limited than AstBuilder
     49
     

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126. #groovylang @glaforge
     Groovy Macros
     • Authoring AST transformations can be verbose:
     50
     def  someVariable  =  new  ConstantExpression("xyz")  
     def  returnStatement  =  new  ReturnStatement(  
            new  ConstructorCallExpression(  
                    ClassHelper.make(SomeCoolClass),  
                    new  ArgumentListExpression(someVariable)  
            )  
     )
     

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127. #groovylang @glaforge
     Groovy Macros
     • With Groovy Macros, it could be simpler:
     51
     def  someVariable  =  macro  {  "xyz"  }  
     def  returnStatement  =  macro  {    
            new  SomeCoolClass($v{  someVariable  })    
     }
     

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128. #groovylang @glaforge
     Groovy Macros
     • With Groovy Macros, it could be simpler:
     51
     def  someVariable  =  macro  {  "xyz"  }  
     def  returnStatement  =  macro  {    
            new  SomeCoolClass($v{  someVariable  })    
     }
     Special « macro » command
     

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129. #groovylang @glaforge
     Groovy Macros
     • With Groovy Macros, it could be simpler:
     51
     def  someVariable  =  macro  {  "xyz"  }  
     def  returnStatement  =  macro  {    
            new  SomeCoolClass($v{  someVariable  })    
     }
     Special « macro » command
     Quasi-quotation
     

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130. @glaforge
     #groovylang
     Groovy 3.0
     

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131. View Slide

132. @glaforge
     #groovylang
     Rewriting the
     Groovy grammar
     with Antlr v4
     Antlr v4 Grammar
     

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133. #groovylang @glaforge
     Antlr v4 grammar
     • Problems
     • Groovy still uses Antlr v2!
     • but version 3 and 4 are out
     • Groovy’s grammar evolved from a Java grammar
     • harder to fix and evolve, especially with Antlr v2
     • Advantages
     • Start from a clean slate
     • Antlr 4 more tolerant 

     and powerful regarding ambiguities
     • Time to clean some grammar & syntax warts!
     • Need to implement the Java 8 constructs!
     55
     

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134. #groovylang @glaforge
     Antlr v4 grammar
     • Problems
     • Groovy still uses Antlr v2!
     • but version 3 and 4 are out
     • Groovy’s grammar evolved from a Java grammar
     • harder to fix and evolve, especially with Antlr v2
     • Advantages
     • Start from a clean slate
     • Antlr 4 more tolerant 

     and powerful regarding ambiguities
     • Time to clean some grammar & syntax warts!
     • Need to implement the Java 8 constructs!
     55
     A « Google Summer of Code »
     student helped kick start it
     

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135. @glaforge
     #groovylang
     Java 8 language support
     

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136. #groovylang @glaforge
     Java 8 support
     • Additional grammar & semantic features to support
     • to keep saying Groovy / Java interoperability is awesome!
     • New in Java 8
     • lambdas
     • method references
     • default methods in interfaces
     • stream API, date / time API
     • annotations on types & repeated annotations
     57
     

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137. #groovylang @glaforge
     Java 8 support
     • Additional grammar & semantic features to support
     • to keep saying Groovy / Java interoperability is awesome!
     • New in Java 8
     • lambdas
     • method references
     • default methods in interfaces
     • stream API, date / time API
     • annotations on types & repeated annotations
     57
     Groovy had already:
     closures, method pointers, mixins,
     enriched collection & time APIs
     

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138. @glaforge
     #groovylang
     MOP 2
     

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139. #groovylang @glaforge
     Goals for the new MOP
     • Leverage & build upon JDK 7+ invoke dynamic
     • get Java-like performance even for dynamic code
     • Rationalize the sedimentation of meta-programming
     • more coherence, less corner cases & inconsistencies
     • Provide a notion of « realm »
     • shield users of « monkey patching »
     • finer-grained control of meta-programming reach
     • Private visibility anyone?
     59
     

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140. @glaforge
     #groovylang
     Summary
     

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141. View Slide

142. Groovy rocks the JVM 

     since 2003!
     

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143. @glaforge
     #groovylang
     Q & A
     

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144. View Slide

145. #groovylang @glaforge
     Image credits
     • London:
     • http://www.excel-london.co.uk/media/26705/why-london-hero-shot.jpg
     • http://libertychurchlondon.com/wp-content/uploads/2013/01/london1.jpg
     • http://cdni.wired.co.uk/1920x1280/k_n/London_5.jpg
     • http://www.100percentoptical.com/images/2014/10/london.jpg
     • Big rock: http://wallpaper.preview-reviews.com/12852-red-rocks-in-a-snowstorm
     • Android robot: http://crackberry.com/sites/crackberry.com/files/styles/large/public/topic_images/2013/ANDROID.png?itok=xhm7jaxS
     • Modern MOP: http://i933.photobucket.com/albums/ad179/autobin/Wonder%20Mop/wondermop4.jpg
     • Jason: http://static.comicvine.com/uploads/original/3/32405/1031312-jason_19_inch_figure_l.jpg
     • Jigsaw: http://www.psdgraphics.com/file/psd-jigsaw-icon.jpg
     • Many thanks: http://www.trys.ie/wp-content/uploads/2013/06/many-thanks.jpg
     64
     

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