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  1. #include <memory>
  2. #include <functional>
  3. #include <iostream>
  4.  
  5. struct function_wrapper
  6. {
  7.   virtual ~function_wrapper() {}
  8. };
  9. template <typename... Args>
  10. struct variadic_function : function_wrapper
  11. {
  12.   variadic_function(std::function<void(Args...)> f) : f_(std::move(f)) {}
  13.   void operator()(Args &&... args) { f_(std::forward<Args>(args)...); }
  14.  
  15. private:
  16.   std::function<void(Args...)> f_;
  17. };
  18.  
  19. class dispatcher
  20. {
  21. public:
  22.   template <typename... Args>
  23.   void register_event(std::function<void(Args...)> f)
  24.   {
  25.     f_ = std::make_shared<variadic_function<Args...>>(std::move(f));
  26.   }
  27.  
  28.   template <typename... Args>
  29.   void post(Args &&... args)
  30.   {
  31.     auto f = std::dynamic_pointer_cast<variadic_function<Args...>>(f_);
  32.     if (f)
  33.     {
  34.       (*f)(std::forward<Args>(args)...);
  35.     }
  36.   }
  37.  
  38. private:
  39.   std::shared_ptr<function_wrapper> f_;
  40. };
  41.  
  42. int main()
  43. {
  44.   dispatcher d;
  45.   std::function<void(int)> f = [](int a) { std::cout << a << "\n"; };
  46.   d.register_event(f);
  47.   d.post(42);
  48.  
  49.   return 0;
  50. }
  51.  
Success #stdin #stdout 0s 3460KB
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42
https://ideone.com/Obya2u
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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