Groovy Goodness: Mixin Functionality to Classes

In a previous blog post we learned how to use Categories to add functionality to existing class. We had to use the use keyword to define a block in which the Category was valid. But we can also add new functionality with the @Mixin compile-time annotation or at runtime with the mixin() method (GDK extension to Class).

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class Pirate {     def talk(text) {         "Aargh, walk the plank. ${text}"     } }   // Compile time mixin to Talk class. This add all // methods from Pirate to Talk. @Mixin(Pirate)  class Talk {}   assert 'Aargh, walk the plank. Give me a bottle of rum.' == new Talk().talk("Give me a bottle of rum.")

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import org.apache.commons.lang.StringUtils   class Parrot {     static String speak(String text) {         /Parrot says "$text"/     } }   // Runtime mixin on String class. // mixin() is a GDK extension to Class. String.mixin Parrot, StringUtils   assert 'Parrot says "mrhaki"' == 'mrhaki'.speak() assert 'Groovy is so much...' == 'Groovy is so much fun.'.abbreviate(20)  // StringUtils mixin.