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  1. #include <cstdio>
  2.  
  3. struct GenericObject;
  4. typedef void (GenericObject::*GenericMethod)(GenericObject const&);
  5.  
  6. template<class HandlerBase, class ArgBase>
  7. struct CallTraits
  8. {
  9. 	typedef void(*CallFunc)(HandlerBase*, GenericMethod, ArgBase const&);
  10.  
  11. 	template<class TheHandler, class TheArg>
  12. 	static void callfunc(HandlerBase* h, GenericMethod m, ArgBase const& a)
  13. 	{
  14. 		typedef void (TheHandler::*TheMethod)(TheArg const&);
  15.  
  16. 		TheHandler*   th = (TheHandler*)h;
  17. 		TheMethod     tm = (TheMethod)m;
  18. 		TheArg const& ta = (TheArg const&)a;
  19.  
  20. 		printf(" < %p->...(*%p)\n", h,  &a);
  21. 		printf(" > %p->...(*%p)\n", th, &ta);
  22. 		(th->*tm)(ta);
  23. 	}
  24.  
  25. 	struct Delegate
  26. 	{
  27. 		HandlerBase*  h;
  28. 		GenericMethod m;
  29. 		CallFunc      c;
  30. 	};
  31.  
  32. 	template<class TheHandler, class TheArg>
  33. 	static Delegate make_delegate(TheHandler* th, void (TheHandler::*tm)(TheArg const&))
  34. 	{
  35. 		Delegate d = { (HandlerBase*)th, (GenericMethod)tm, &callfunc<TheHandler,TheArg> };
  36. 		return d;
  37. 	}
  38.  
  39. 	static void call_delegate(Delegate const& d, ArgBase const& a)
  40. 	{
  41. 		d.c(d.h, d.m, a);
  42. 	}
  43. };
  44.  
  45. struct A0 { int x; virtual ~A0() {} };
  46. struct A1 { int y; };
  47. struct A : A0, A1 {};
  48.  
  49.  
  50. struct H0 { int x; virtual ~H0() {} };
  51. struct H1 { int y; virtual ~H1() {} };
  52. struct H : H0, H1
  53. {
  54. 	virtual void foo(A const& a)
  55. 	{
  56. 		printf(" = %p->foo(*%p)\n", this, &a);
  57. 	}
  58. };
  59.  
  60.  
  61.  
  62.  
  63.  
  64. int main()
  65. {
  66. 	typedef CallTraits<H1, A1> CT;
  67.  
  68. 	A a; H h;
  69.  
  70. 	printf("directly:\n");
  71. 	h.foo(a);
  72.  
  73. 	printf("delegated:\n");
  74. 	CT::Delegate d = CT::make_delegate(&h, &H::foo);
  75. 	printf("delegate: %p %p  sizeof(fun)=%d sizeof(method)=%d\n", d.h, d.c, sizeof(d.c), sizeof(d.m));
  76. 	CT::call_delegate(d, a);
  77. }
  78.  
Success #stdin #stdout 0s 3296KB
comments (?)
stdin
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Standard input is empty
stdout
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directly:
 = 0xbf9fb780->foo(*0xbf9fb774)
delegated:
delegate: 0xbf9fb788 0x80487a0  sizeof(fun)=4 sizeof(method)=8
 < 0xbf9fb788->...(*0xbf9fb77c)
 > 0xbf9fb780->...(*0xbf9fb774)
 = 0xbf9fb780->foo(*0xbf9fb774)
https://ideone.com/QZrLxf
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
public

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