jmultimethod

multimethods for Java using annotations
git clone https://logand.com/git/jmultimethod.git/
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AsteroidTest.java (3543B)

      1 // Copyright (c) 2009, 2015 Tomas Hlavaty All rights reserved.
      2 
      3 // Redistribution and use in source and binary forms, with or without
      4 // modification, are permitted provided that the following conditions
      5 // are met:
      6 
      7 // Redistributions of source code must retain the above copyright
      8 // notice, this list of conditions and the following
      9 // disclaimer. Redistributions in binary form must reproduce the above
     10 // copyright notice, this list of conditions and the following
     11 // disclaimer in the documentation and/or other materials provided
     12 // with the distribution.
     13 
     14 // Neither the name of jmultimethod nor the names of its contributors
     15 // may be used to endorse or promote products derived from this
     16 // software without specific prior written permission.
     17 
     18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     21 // FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     22 // COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     23 // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     24 // (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     25 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26 // HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
     27 // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
     29 // OF THE POSSIBILITY OF SUCH DAMAGE.
     30 
     31 // http://en.wikipedia.org/wiki/Multiple_dispatch
     32 
     33 package jmultimethod;
     34 
     35 public class AsteroidTest {
     36 
     37     class Asteroid {}
     38 
     39     class Spaceship {}
     40 
     41     @Multi("collide")
     42     public void collideOO(Object X, Object Y) {
     43         log("?? Bang, what happened? ", X, Y);
     44     }
     45 
     46     @Multi("collide")
     47     public void collideAA(Asteroid X, Asteroid Y) {
     48         log("AA Look at the beautiful fireworks! ", X, Y);
     49     }
     50 
     51     @Multi("collide")
     52     public void collideAS(Asteroid X, Spaceship Y) {
     53         log("AS Is it fatal? ", X, Y);
     54     }
     55 
     56     @Multi("collide")
     57     public void collideSA(Spaceship X, Asteroid Y) {
     58         log("SA Is it fatal? ", X, Y);
     59     }
     60 
     61     @Multi("collide")
     62     public void collideSS(Spaceship X, Spaceship Y) {
     63         log("SS Who's fault was it? ", X, Y);
     64     }
     65 
     66     @Multi("collide")
     67     public void collide1S(String X, Spaceship Y) {
     68         log("1S any string? ", X, Y);
     69     }
     70 
     71     @Multi("collide")
     72     public void collide2S(@V("hi") String X, Spaceship Y) {
     73         log("2S 'hi' value? ", X, Y);
     74     }
     75 
     76     protected Multimethod mm = new Multimethod("collide", getClass());
     77 
     78     public void collide(Object X, Object Y) {
     79         mm.invoke(this, X, Y);
     80     }
     81 
     82     public void run() {
     83         Object A = new Asteroid();
     84         Object S = new Spaceship();
     85         collide(A, A);
     86         collide(A, S);
     87         collide(S, A);
     88         collide(S, S);
     89         collide(A, 1);
     90         collide(2, A);
     91         collide(S, 3);
     92         collide(4, S);
     93         collide(5, null);
     94         collide(null, null);
     95         collide("hi", S);
     96         collide("hello", S);
     97     }
     98 
     99     public void log(Object... args) {
    100         for(Object o: args) {
    101             if(o instanceof String) {
    102                 System.out.print(" " + (String) o);
    103             } else {
    104                 System.out.print(" " + o);
    105             }
    106         }
    107         System.out.println();
    108     }
    109 
    110     public static void main(String[] args) throws Exception {
    111         AsteroidTest t = new AsteroidTest();
    112         t.run();
    113     }
    114 }