doubledispatch.groovy

// Main
IElement element = getElement()
printer(element)

// Classes
IElement getElement() {
    // simulate not knowing the type of element at runtime
    if (new Random().nextInt() % 2 == 0) {
        return new Element1(var1: "hello")
    } else {
        return new Element2(var2: "world")
    }
}

def printer(Element1 e1) {
    println e1.var1
}

def printer(Element2 e2) {
    println e2.var2
}

interface IElement {
}

class Element1 implements IElement {
    String var1
}

class Element2 implements IElement {
    String var2
}