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  1. #include <iostream>
  2.  
  3. class Null { };
  4.  
  5. #define DELEGATE(returnType, ...) Delegate<returnType (*)(__VA_ARGS__), returnType (Null::*)(__VA_ARGS__)>
  6. #define ARGS(...) __VA_ARGS__
  7.  
  8. template<class _FunctionType, class _MemberType>
  9. struct Delegate {
  10. 	typedef _FunctionType FunctionType;
  11. 	typedef _MemberType MemberType;
  12.  
  13. 	Null* mpThis;
  14. 	union DelPtr {
  15. 		_FunctionType asStatic;
  16. 		_MemberType asMember;
  17. 		DelPtr(_FunctionType p) : asStatic(p) { }
  18. 		DelPtr(_MemberType p) : asMember(p) { }
  19. 	};
  20. 	DelPtr mpfn;
  21.  
  22. 	Delegate(_FunctionType pfn) : mpThis(NULL), mpfn(pfn) { }
  23. 	Delegate(_MemberType pfn, void* pThis) : mpThis((Null*)pThis), mpfn(pfn) { }
  24. };
  25.  
  26. #define INVOKE(_delegate, ...) ( \
  27. 	(_delegate).mpThis ? \
  28. 		(((_delegate).mpThis)->*((_delegate).mpfn.asMember))(__VA_ARGS__) \
  29. 	: \
  30. 		((_delegate).mpfn.asStatic)(__VA_ARGS__) \
  31. 	)
  32.  
  33.  
  34. float test1(int a, int b) {
  35. 	std::cout << "a:" << a << std::endl;
  36. 	std::cout << "b:" << b << std::endl;
  37. 	return 7.0f;
  38. }
  39.  
  40. class TestClass {
  41. public:
  42. 	double x;
  43. 	float test2(int a, int b) {
  44. 		std::cout << "TestClass a:" << a << std::endl;
  45. 		std::cout << "TestClass b:" << b << std::endl;
  46. 		std::cout << "TestClass x:" << x << std::endl;
  47. 		return 5.0f;
  48. 	}
  49. };
  50.  
  51. class TestClass2 {
  52. public:
  53. 	char c;
  54. 	float  test3(int a, int b) {
  55. 		std::cout << "TestClass2 a:" << a << std::endl;
  56. 		std::cout << "TestClass2 b:" << b << std::endl;
  57. 		std::cout << "TestClass2 c:" << c << std::endl;
  58. 		return 3.0f;
  59. 	}
  60. };
  61.  
  62. // Declare MANUALLY
  63. // typedef float (*FnStatic)(int, int) ;
  64. // typedef float (NullClass::*FnMember)(int, int);
  65. // typedef Delegate<FnStatic, FnMember> Delegate1;
  66.  
  67. // Declare using DELEGATE macro
  68. typedef DELEGATE(float, ARGS(int, int)) Delegate1;
  69.  
  70. int main() {
  71. 	TestClass obj;
  72. 	obj.x = 23.3;
  73. 	TestClass2 obj2;
  74. 	obj2.c = 'h';
  75.  
  76. 	std::cout << "test\n";
  77.  
  78. 	Delegate1 d = Delegate1(test1);
  79. 	Delegate1 e = Delegate1((Delegate1::MemberType)&TestClass::test2, &obj);
  80. 	Delegate1 f = Delegate1((Delegate1::MemberType)&TestClass2::test3, &obj2);
  81.  
  82. 	std::cout << "d return value: " << (INVOKE(d, ARGS(5, 6))) << std::endl;
  83. 	std::cout << "e return value: " << (INVOKE(e, ARGS(8, 9))) << std::endl;
  84. 	std::cout << "f return value: " << (INVOKE(f, ARGS(1, 2))) << std::endl;
  85.  
  86. 	int x;
  87. 	std::cin >> x;
  88. 	return 0;
  89. }
Success #stdin #stdout 0.01s 2688KB
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Standard input is empty
stdout
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test
a:5
b:6
d return value: 7
TestClass a:8
TestClass b:9
TestClass x:23.3
e return value: 5
TestClass2 a:1
TestClass2 b:2
TestClass2 c:h
f return value: 3
https://ideone.com/CNJDi
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
secret

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