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  1. #include <iostream>
  2.  
  3. static void _pass() {}
  4. struct Iman
  5. {
  6.     static void salam() {std::cout << "salam";}
  7. };
  8.  
  9. template<typename Class>
  10. struct HasSalam
  11. {
  12.     typedef char _1Byte;
  13.     typedef struct { char a[2]; } _2Bytes;
  14.     template<typename __Class> static _1Byte Check(int __Class::*);
  15.     template<typename __Class> static _2Bytes Check(...);
  16.     enum { result = sizeof(HasSalam<Class>::Check<Class>(0)) == sizeof(_1Byte) };
  17. };
  18.  
  19. template<bool N> struct IF
  20. {
  21. 	static constexpr int Result = 1;
  22. 	template<class A> static void print()
  23. 	{
  24. 		A::salam();
  25. 	}
  26. };
  27. template<> struct IF<false>
  28. {
  29. 	static constexpr int Result = 0;
  30. 	template<class A> static void print()
  31. 	{
  32. 		_pass();
  33. 	}
  34. };
  35. template<class T>
  36. struct PrintIfHasSalamMethod
  37. {
  38. 	static void proceed()
  39. 	{
  40. 		IF<
  41. 			HasSalam<T>::result
  42. 		>::print<T>();
  43. 	}
  44. };
  45. int main()
  46. {
  47.     PrintIfHasSalamMethod<Iman>::proceed();
  48. }
  49.  
Compilation error #stdin compilation error #stdout 0s 15224KB
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stdin
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Standard input is empty
compilation info 
prog.cpp: In static member function ‘static void PrintIfHasSalamMethod<T>::proceed()’:
prog.cpp:42:13: error: expected primary-expression before ‘>’ token
   >::print<T>();
             ^
prog.cpp:42:15: error: expected primary-expression before ‘)’ token
   >::print<T>();
               ^
stdout
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Standard output is empty
https://ideone.com/5IHrxy
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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