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  1. #include <functional>
  2. #include <list>
  3.  
  4. struct MyType {
  5.  
  6.   MyType(int init): mValue(init) { }
  7.  
  8.   void AddHandlerOnValueChanged(std::function<bool(MyType const &, int)> handlerOnValueChanged) {
  9.     mHandlersOnValueChanged.push_back(handlerOnValueChanged);
  10.   }
  11.  
  12.   void ChangeValue(int value) {
  13.     mValue = value;
  14.     NotifyValueChanged(value);
  15.   }
  16.  
  17.   int GetValue(void) const {
  18.     return mValue;
  19.   }
  20.  
  21. private:
  22.  
  23.   void NotifyValueChanged(int value) {
  24.     auto & handlers = mHandlersOnValueChanged; // 長いのでエイリアス
  25.     auto i = handlers.begin();
  26.     auto e = handlers.end();
  27.  
  28.     while(i != e) {    
  29.       if((*i)(*this, value)) {
  30.         ++i;
  31.       } else { // 返り値がfalseならハンドラーを削除
  32.         i = handlers.erase(i);
  33.       }
  34.     }
  35.   }
  36.  
  37.   int mValue;
  38.   std::list<std::function<bool(MyType const &, int)>> mHandlersOnValueChanged; 
  39.  
  40. };
  41.  
  42. #include <iostream>
  43.  
  44. int main(void) {
  45.   MyType obj(100);
  46.  
  47.   obj.AddHandlerOnValueChanged([](MyType const & o, int v) { std::cout << "!" << v << std::endl; return v % 2 == 0; });
  48.   obj.AddHandlerOnValueChanged([](MyType const & o, int v) { std::cout << "*" << v << std::endl; return v % 2 == 1; });
  49.  
  50.   obj.ChangeValue(1);
  51.   obj.ChangeValue(2);
  52.   obj.ChangeValue(3);
  53.  
  54.   return 0;
  55. }
  56.  
Success #stdin #stdout 0s 3020KB
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!1
*1
*2
https://ideone.com/mBgiB
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
secret

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