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  1. #include <iostream>
  2. #include <string>
  3.  
  4. namespace memenum
  5. {
  6.     template <int Counter>
  7. 	struct member_iterator : member_iterator<Counter - 1> { static int const value = Counter; };
  8. 	template <>
  9. 	struct member_iterator<0> { static int const value = 0; };
  10.  
  11. 	template <class This, class Op>
  12. 	void call_for_members(This*, member_iterator<__COUNTER__>, Op const&) { }
  13.  
  14. 	template <class T>
  15. 	struct member_wrapper
  16. 	{
  17. 		T value;
  18. 		member_wrapper(T const &v) : value(v) { }
  19. 	};
  20.  
  21. 	#define DEFINE_MEMBER(type, memname, ...) \
  22. 		struct _##memname##_type : ::memenum::member_wrapper<type> \
  23. 		{ \
  24. 			static int const counter = __COUNTER__; \
  25. 			_##memname##_type() : ::memenum::member_wrapper<type>(__VA_ARGS__) { } \
  26. 			char const* name() const { return #memname; } \
  27. 		} memname; \
  28. 		template <class This, class Op> \
  29. 		friend void call_for_members(This *self, ::memenum::member_iterator<_##memname##_type::counter> i, Op const &op, typename This::_##memname##_type* = nullptr) \
  30. 		{ \
  31. 			call_for_members(self, ::memenum::member_iterator<_##memname##_type::counter - 1>(), op); \
  32. 			op(self->memname); \
  33. 		}
  34.  
  35. 	#define MAKE_MEMBER_ITERATOR() ::memenum::member_iterator<__COUNTER__>()
  36.  
  37. } // namespace
  38.  
  39. namespace test
  40. {
  41.  
  42. 	struct foo
  43. 	{
  44. 		DEFINE_MEMBER(int, a, 2);
  45. 		DEFINE_MEMBER(float, b, 2.5f);
  46.  
  47. 	public:
  48. 		struct Printer
  49. 		{
  50. 			template <class T>
  51. 			void operator ()(T &member) const
  52. 			{
  53. 				std::cout << member.name() << " = " << member.value << std::endl;
  54. 			}
  55. 		};
  56. 		void print() const
  57. 		{
  58. 			call_for_members(this, MAKE_MEMBER_ITERATOR(), Printer());
  59. 		}
  60.  
  61. 		struct Multiplier
  62. 		{
  63. 			int factor;
  64.  
  65. 			template <class T>
  66. 			void operator ()(T &member) const
  67. 			{
  68. 				member.value *= factor;
  69. 			}
  70. 		};
  71.  
  72. 		void multiply(int factor)
  73. 		{
  74. 			Multiplier multi = { factor };
  75. 			call_for_members(this, MAKE_MEMBER_ITERATOR(), multi);
  76. 		}
  77. 	};
  78.  
  79. 	struct bar
  80. 	{
  81. 		DEFINE_MEMBER(char, c, 'd');
  82. 		DEFINE_MEMBER(std::string, d, "hello world");
  83.  
  84. 	public:
  85. 		struct Printer
  86. 		{
  87. 			template <class T>
  88. 			void operator ()(T &member) const
  89. 			{
  90. 				std::cout << member.name() << " = " << member.value << std::endl;
  91. 			}
  92. 		};
  93. 		void print() const
  94. 		{
  95. 			call_for_members(this, MAKE_MEMBER_ITERATOR(), Printer());
  96. 		}
  97. 	};
  98.  
  99. } // namespace
  100.  
  101. int main()
  102. {
  103. 	test::foo test1;
  104. 	test1.print();
  105. 	test1.multiply(5);
  106. 	test1.print();
  107.  
  108. 	const test::bar test2;
  109. 	test2.print();
  110. }
  111.  
Success #stdin #stdout 0s 3028KB
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stdin
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Standard input is empty
stdout
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a = 2
b = 2.5
a = 10
b = 12.5
c = d
d = hello world
https://ideone.com/uv4Ab4
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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