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  1. #include <iostream>
  2. #include <type_traits>
  3.  
  4. template<class OutType>
  5. struct A
  6. {
  7.  
  8. 	template<typename T = OutType, typename... Args>
  9. 	typename std::enable_if<std::is_same<T, void>::value>::type
  10.     operator()(Args && ... args)
  11.     {
  12.     	std::cout << "void (args)" << std::endl;
  13.     }
  14.  
  15.     template<typename T = OutType>
  16. 	typename std::enable_if<std::is_same<T, void>::value>::type
  17.     operator()()
  18.     {
  19.     	std::cout << "void (void)" << std::endl;
  20.     }
  21.  
  22. 	template<typename T = OutType, typename... Args>
  23. 	typename std::enable_if<!std::is_same<T, void>::value, OutType>::type
  24.     operator()(Args && ... args) 
  25.     {
  26.     	std::cout << "!void (args)" << std::endl;
  27.     	return OutType();
  28.     }
  29.  
  30.     template<typename T = OutType>
  31.     typename std::enable_if<!std::is_same<T, void>::value, OutType>::type
  32.     operator()()
  33.     {
  34.     	std::cout << "!void (void)" << std::endl;
  35.     	return OutType();
  36.     }
  37. };
  38.  
  39. int main()
  40. {
  41.     A<int> a1;
  42.  
  43.     a1(56, 'e');
  44.     a1();
  45.  
  46.     A<void> a2;
  47.  
  48.     a2(13, 0.66f);
  49.     a2();
  50.  
  51.     return 0;
  52. }
Success #stdin #stdout 0s 16064KB
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stdin
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Standard input is empty
stdout
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!void (args)
!void (void)
void (args)
void (void)
https://ideone.com/GDPspp
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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