gistfile1.java

// Example for http://gist.github.com/51089

public class AsteroidTest {

    class Asteroid {}

    class Spaceship {}

    @Multi("collide")
    public void collideOO(Object X, Object Y) {
       log("?? Bang, what happened? ", X, Y);
    }

    @Multi("collide")
    public void collideAA(Asteroid X, Asteroid Y) {
        log("AA Look at the beautiful fireworks! ", X, Y);
    }

    @Multi("collide")
    public void collideAS(Asteroid X, Spaceship Y) {
        log("AS Is it fatal? ", X, Y);
    }

    @Multi("collide")
    public void collideSA(Spaceship X, Asteroid Y) {
        log("SA Is it fatal? ", X, Y);
    }

    @Multi("collide")
    public void collideSS(Spaceship X, Spaceship Y) {
        log("SS Who's fault was it? ", X, Y);
    }

    @Multi("collide")
    public void collide1S(String X, Spaceship Y) {
        log("1S any string? ", X, Y);
    }

    @Multi("collide")
    public void collide2S(@V("hi") String X, Spaceship Y) {
        log("2S 'hi' value? ", X, Y);
    }

    protected Multimethod mm = new Multimethod("collide", getClass());

    public void collide(Object X, Object Y) {
        mm.invoke(this, X, Y);
    }

    public void run() {
        Object A = new Asteroid();
        Object S = new Spaceship();
        collide(A, A);
        collide(A, S);
        collide(S, A);
        collide(S, S);
        collide(A, 1);
        collide(2, A);
        collide(S, 3);
        collide(4, S);
        collide(5, null);
        collide(null, null);
        collide("hi", S);
        collide("hello", S);
    }

    public void log(Object... args) {
        for(Object o: args) {
            if(o instanceof String) {
                System.out.print(" " + (String) o);
            } else {
                System.out.print(" " + o);
            }
        }
        System.out.println();
    }

    public static void main(String[] args) throws Exception {
        AsteroidTest t = new AsteroidTest();
        t.run();
    }
}