Groovy Metaclass

One of my favourites Groovy´s features is its MOP architecture. It allow us introducing new methods at runtime thanks to the metaClass.

We can define a new class

class SampleClass {

// class field

def propertyOne

// one sample Closure

def closureOne = {

println "I´m the closure one"

}

}

Now we add a new method at runtime

SampleClass.metaClass.runtimeAddedMethod = {

println "I´m runtimeAddedMethod"

}

Declare a new instance an test all the methods

def instance = new SampleClass()

Call to the closure declared in class definition

instance.closureOne()

Call to the method added at runtime

instance.runtimeAddedMethod()

We add a method to the "instance" too

instance.metaClass.instanceRuntimeAddedMethod = {

println "I´m the method added at runtime to a single instance"

}

instance.instanceRuntimeAddedMethod()

Bye!!