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  1. #include <type_traits>
  2. #include <iostream>
  3.  
  4. template<typename TDerived> class
  5. t_ImplicitlyConvertableToAnything
  6. {
  7. 	public: template
  8. 	<
  9. 		typename TTarget
  10. 	,	typename TEnabled = typename ::std::enable_if_t<::std::is_integral<TTarget>::value>
  11. 	>
  12. 	operator TTarget(void) const
  13. 	{
  14. 		auto const & self{static_cast<const TDerived &>(*this)};
  15. 		return(self.template CheckedConversion_To_Integral<TTarget>());
  16. 	}
  17. };
  18.  
  19. template<typename TDerived> class
  20. t_ExplicitlyConvertableToAnything
  21. {
  22. 	public: template
  23. 	<
  24. 		typename TTarget
  25. 	,	typename TEnabled = typename ::std::enable_if_t<!::std::is_integral<TTarget>::value>
  26. 	> explicit
  27. 	operator TTarget(void) const
  28. 	{
  29. 		auto const & self{static_cast<const TDerived &>(*this)};
  30. 		return(self.template CheckedConversion_To_NonIntegral<TTarget>());
  31. 	}
  32. };
  33.  
  34. class
  35. t_ConvertableToAnything
  36. :	public t_ImplicitlyConvertableToAnything<t_ConvertableToAnything>
  37. ,	public t_ExplicitlyConvertableToAnything<t_ConvertableToAnything>
  38. {
  39. 	public: template<typename TTarget> decltype(auto)
  40. 	CheckedConversion_To_Integral(void) const
  41. 	{
  42. 		return(static_cast<TTarget>(1));
  43. 	}
  44.  
  45. 	public: template<typename TTarget> decltype(auto)
  46. 	CheckedConversion_To_NonIntegral(void) const
  47. 	{
  48. 		return(static_cast<TTarget>(3.14));
  49. 	}
  50. };
  51.  
  52.  
  53. int main()
  54. {
  55. 	t_ConvertableToAnything c;
  56. 	::std::cout << ([](int x){return(x);})(c) << ::std::endl;
  57. 	::std::cout << static_cast<float>(c) << ::std::endl;
  58. 	return(0);
  59. }
  60.  
Success #stdin #stdout 0s 16064KB
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1
3.14
https://ideone.com/zqbRk2
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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