RosettaCodeData/Task/Delegates/Objeck/delegates.objeck

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interface Thingable {
method : virtual : public : Thing() ~ String;
}
class Delegator {
@delegate : Thingable;
New() {
}
method : public : SetDelegate(delegate : Thingable) ~ Nil {
@delegate := delegate;
}
method : public : Operation() ~ String {
if(@delegate = Nil) {
return "default implementation";
}
else {
return @delegate->Thing();
};
}
}
class Delegate implements Thingable {
New() {
}
method : public : Thing() ~ String {
return "delegate implementation";
}
}
class Example {
function : Main(args : String[]) ~ Nil {
# Without a delegate:
a := Delegator->New();
Runtime->Assert(a->Operation()->Equals("default implementation"));
# With a delegate:
d := Delegate->New();
a->SetDelegate(d);
Runtime->Assert(a->Operation()->Equals("delegate implementation"));
# Same as the above, but with an anonymous class:
a->SetDelegate(Base->New() implements Thingable {
method : public : Thing() ~ String {
return "anonymous delegate implementation";
}
});
Runtime->Assert(a->Operation()->Equals("anonymous delegate implementation"));
}
}