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  1. import std.stdio;
  2. import std.traits;
  3.  
  4. struct WM {
  5.   size_t value;
  6. }
  7.  
  8. bool hasWMAttr(alias T)(WM wm) {
  9.   foreach(attr; __traits(getAttributes, T)) {
  10.     static if(is(typeof(attr) == WM))
  11.       if(attr == wm) return true;
  12.   }
  13.   return false;
  14. }
  15.  
  16. mixin template Dispatcher()
  17. {
  18.   void dispatch(T)(T msg)
  19.   if(hasMember!(T, "message") && is(typeof(T.message) == size_t))
  20.   {
  21.     alias void delegate(T msg) DG;
  22.     foreach(m; __traits(derivedMembers, typeof(this))) {
  23.       foreach(func; __traits(getOverloads, typeof(this), m)) {
  24.         static if(is(ParameterTypeTuple!(typeof(func)) == ParameterTypeTuple!(DG))) {
  25.           if(hasWMAttr!func(WM(msg.message))) {
  26.             func(msg);
  27.           }
  28.         }
  29.       }
  30.     }
  31.   }
  32. }
  33.  
  34. // Sample
  35.  
  36. struct Message {
  37.   size_t message;
  38.   // wparam, lparam...
  39. }
  40.  
  41. class Test {
  42.   mixin Dispatcher;
  43.   [WM(10)]
  44.   void wm10(Message msg) {
  45.     writeln("Received message10");
  46.   }
  47.   [WM(20)]
  48.   void wm20(Message msg) {
  49.     writeln("Received message20");
  50.   }
  51.   //[WM(10), WM(20)]
  52.   @WM(10) @WM(20)
  53.   void wm(Message msg) {
  54.     writeln("Received message: ", msg.message);
  55.   }
  56.   /+
  57.   // Linker error
  58.   @WM(100)
  59.   void wm(Message msg) { }
  60.   +/
  61. }
  62.  
  63. void main()
  64. {
  65.   auto test = new Test();
  66.   test.dispatch(Message(10));
  67.   test.dispatch(Message(20));
  68. }
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https://ideone.com/W66pN2
language:
D (dmd 2.085.0)
created:
11 years ago
visibility:
public

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