Controlled extension

By default, EVL multimethods are permissive and allow to override and extend existing match methods. However it is possible to restrict and emulate the “final” qualifier.

First it is possible to define a multimethod that is not overridable:

Method1<Integer> method = new Method1<Void>()
		.notOverridable()
		.add(new Cases() {
	
	int match(A a) {
		return 1;  
	}
	
	int match(B b) {
		return 2;  
	}
	
});

This way, trying to add a new match method for A or B will lead to the throw of a MethodNotAddedException:

try {
	method.add(new Cases() {
	
		int match(A a) {
			return 1;  
		}
}
catch (Throwable e) {
	e.printStackTrace();
}

Second it is possible to make the multimethod final meaning that it is not possible to extend it anymore:

method.setFinal();

So that add a new match method will lead to the throw of a MethodNotAddedException:

try {
	method.add(new Cases() {
	
		int match(C c) {
			return 3;  
		}
}
catch (Throwable e) {
	e.printStackTrace();
}

Once the multimethod is set final, it is impossible to go back and it will remain final for the rest of its existence.