MultiCastableDelegate(D)

MultiCastableDelegate(D)

//マルチキャストなデリゲート
import std.traits;
struct MultiCastableDelegate(T) if(isCallable!T){
  import std.container;
  private DList!T funcs;
  alias S = ReturnType!T;

  public S opCall(ParameterTypeTuple!T args...){
    static if(__traits(compiles, {S x;})){
      S a;
      funcs.each!((func){
          a = func(args);
      });
      return a;
    }else{
      funcs.each!((func){
        func(args);
      });
    }
  }
  public auto opBinary(string op)(T arg){
    static if(op == "+"){
      auto a = this;
      a += arg;
      return a;
    }else static if(op == "-"){
      auto a = this;
      a -= arg;
      return a;
    }
  }
  public auto opOpAssign(string op)(T arg){
    static if(op == "+"){
      this.addFunc(arg);
    }else static if(op == "-"){
      this.removeFunc(arg);
    }
  }
  public auto opSlice(){
    return funcs[];
  }
  private void addFunc(T arg){
    funcs.insertBack(arg);
  }
  private void removeFunc(T arg){
    import std.algorithm, std.range;
    funcs.linearRemove(find(funcs[], arg).take(1));
  }
}
unittest{
  import std.array;
  "雲丹おいしい".log;
  MultiCastableDelegate!(string function(string, string)) d;
  auto a = function string (string a, string b){a.log; b.log; return "ゆうあし";};
  d += a;
  d = d + &test;
  d("hoge", "hage");
  d[].map!((f) => f("hoge", "hage")).array.each!((a){a.log;});
  //rtn.log;
}

string test(string a, string b){
  a.log;
  b.log;
  return "ハゲ";
}