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  1. #include <utility>
  2. #include <cassert>
  3.  
  4.  
  5. template<typename T, typename R, typename ...Args>
  6. class mem_fun_t {
  7.  
  8.    using method_ptr_t = R (T::*)(Args...);
  9.  
  10. public:
  11.    mem_fun_t(method_ptr_t const methodPtr_) : methodPtr_(methodPtr_) {
  12.       assert(methodPtr_);
  13.    }
  14.  
  15.    R operator ()(T * const objectPtr, Args && ...args) const {
  16.       assert(objectPtr);
  17.       return (objectPtr->*methodPtr_)(std::forward<Args>(args)...);
  18.    }
  19.  
  20.    R operator ()(T & objectRef, Args && ...args) const {
  21.       return (objectRef.*methodPtr_)(std::forward<Args>(args)...);
  22.    }
  23.  
  24. private:
  25.    method_ptr_t const methodPtr_;
  26. };
  27.  
  28. template<typename T, typename R, typename ...Args>
  29. mem_fun_t<T, R, Args...> mem_fun(R (T::*pointer)(Args...)) {
  30.    return {pointer};
  31. }
  32.  
  33. template<typename T, typename R, typename ...Args>
  34. mem_fun_t<T const, R, Args...> mem_fun(R (T::*pointer)(Args...) const) {
  35.    return {pointer};
  36. }
  37.  
  38.  
  39. struct test {
  40.  
  41.    int mutable_method(float f, double d) {
  42.       return static_cast<int>(f + d);
  43.    }
  44.  
  45.    int const_method(float f, double d) const {
  46.       return static_cast<int>(f + d);
  47.    }
  48. };
  49.  
  50.  
  51. int main() {
  52.    test mutableObject;
  53.    test const constObject; 
  54.  
  55.    auto const mutableBinded = mem_fun(&test::mutable_method);
  56.    assert(mutableBinded(&mutableObject, 5.56f, 7.91) == 13);
  57.    assert(mutableBinded(mutableObject, 78.9f, 1.2) == 80);   
  58.  
  59.    auto const constBinded = mem_fun(&test::const_method);
  60.    assert(constBinded(&mutableObject, 4.51f, 13.6) == 18);
  61.    assert(constBinded(&constObject, -123.1f, 45.5) == -77);
  62.    assert(constBinded(mutableObject, -98.f, 56.4) == -41);
  63.    assert(constBinded(constObject, 45.56f, 45.5) == 91);   
  64. }
  65.  
Success #stdin #stdout 0s 2892KB
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https://ideone.com/3wKCpl
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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