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  1. #include <stdio.h>
  2.  
  3. #define TRAIT_DEF( trait_name ) \
  4. 	class Trait_##trait_name \
  5. 	{ \
  6. 	public: \
  7. 		virtual void trait_name( void ) = 0; \
  8. 	}
  9. #define TRAIT_USE( trait_name, class_name ) \
  10. 	Trait_##trait_name##_##class_name m_Trait_##trait_name; \
  11. 	public: \
  12. 	Trait_##trait_name* GetTrait_##trait_name( void ){ return &m_Trait_##trait_name; } \
  13. 	friend class Trait_##trait_name##_##class_name
  14. #define TRAIT_INIT( trait_name ) m_Trait_##trait_name(this)
  15. #define TRAIT_HELPER_DEF( trait_name, class_name ) \
  16. 	class Trait_##trait_name##_##class_name : public Trait_##trait_name \
  17. 	{ \
  18. 		class class_name* m_pTarget; \
  19. 	public: \
  20. 		Trait_##trait_name##_##class_name( class_name* p ) : m_pTarget( p ){} \
  21. 		virtual void trait_name( void ); \
  22. 	}
  23. #define TRAIT_HELPER_DEF_AFTER( trait_name, class_name ) \
  24. 		void Trait_##trait_name##_##class_name::trait_name( void ) \
  25. 		{ \
  26. 			m_pTarget->trait_name(); \
  27. 		}
  28.  
  29. TRAIT_DEF( Draw );
  30. TRAIT_DEF( Update );
  31. TRAIT_DEF( Jump );
  32.  
  33. TRAIT_HELPER_DEF( Draw, A );
  34. TRAIT_HELPER_DEF( Update, A );
  35. class A
  36. {
  37. 	TRAIT_USE( Draw, A );
  38. 	TRAIT_USE( Update, A );
  39. public:
  40. 	A() : TRAIT_INIT( Draw ), TRAIT_INIT( Update ){}
  41. 	void Draw( void ){ printf( "A::Draw\n" ); }
  42. 	void Update( void ){ printf( "A::Update\n" ); }
  43. };
  44. TRAIT_HELPER_DEF_AFTER( Draw, A );
  45. TRAIT_HELPER_DEF_AFTER( Update, A );
  46.  
  47. TRAIT_HELPER_DEF( Draw, B );
  48. TRAIT_HELPER_DEF( Jump, B );
  49. class B
  50. {
  51. 	TRAIT_USE( Draw, B );
  52. 	TRAIT_USE( Jump, B );
  53. public:
  54. 	B() : TRAIT_INIT( Draw ), TRAIT_INIT( Jump ){}
  55. 	void Draw( void ){ printf( "B::Draw\n" ); }
  56. 	void Jump( void ){ printf( "B::Jump\n" ); }
  57. };
  58. TRAIT_HELPER_DEF_AFTER( Draw, B );
  59. TRAIT_HELPER_DEF_AFTER( Jump, B );
  60.  
  61. int main( void )
  62. {
  63. 	A a;
  64. 	B b;
  65. 	Trait_Draw* pDrawA = a.GetTrait_Draw();
  66. 	Trait_Draw* pDrawB = b.GetTrait_Draw();
  67. 	pDrawA->Draw();
  68. 	pDrawB->Draw();
  69. 	Trait_Update* pUpdate = a.GetTrait_Update();
  70. 	pUpdate->Update();
  71. 	Trait_Jump* pJump = b.GetTrait_Jump();
  72. 	pJump->Jump();
  73.     return 0;
  74. }
Success #stdin #stdout 0s 2684KB
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stdin
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Standard input is empty
stdout
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A::Draw
B::Draw
A::Update
B::Jump
https://ideone.com/6O3GTF
language:
C++ 4.3.2 (gcc-4.3.2)
created:
10 years ago
visibility:
secret

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