Switch

The EVL library provides the Switch class which is a syntactic sugar for a multimethod of dimension 1 with void return type.

Let’s take a simple hierarchy:

public class A {
	
	public int a = 2;
}

public class B extends A {
	
	public B(int a) {
		this.a = a;
	}
}

The Switch class implements a general switch construct based on the dynamic type. We add a non-virtual parameter to show that it is accepted :

Switch test = Switch.with(new Cases() {
				
	void match(Integer i, int v) {
		System.out.println("Integer " + (i + v));
	}
	
	void match(String s, int v) {
		System.out.println("String " + s + v);
	}
	
	void match(A a, int v) {
		System.out.println("A " + (a.a + v));
	}
});

We can use it:

test.invoke(Integer.valueOf(12), 3);
test.invoke(new String("beautiful"), 11);
test.invoke(new B(5), 4);
test.invoke(Float.valueOf(13.1f), 5);

Everything will be fine except for the last invocation: there is no compatible method because a Float object cannot be cast into an Integer object.

The Switch class can be used anywhere with any basic types, however only in their Object form preventing from number casting. This rule also applies to standard multimethods.