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  1. #include <type_traits>
  2. #include <utility>
  3. #include <iostream>
  4. #include <limits>
  5.  
  6. template<typename T>
  7. class Foo
  8. {
  9.     T bar;
  10.  
  11.     template<typename R>
  12.     Foo(R&&, typename std::enable_if<!std::is_convertible<R,T>::value>::type * = 0) = delete;
  13. public:    
  14.     template<typename R>
  15.     Foo(R &&bar, typename std::enable_if<std::is_convertible<R,T>::value>::type * = 0)
  16.         : bar(std::forward<R>(bar))
  17.  
  18.     {
  19.         std::cout << "Initialized from rvalue reference: " <<
  20.             std::is_rvalue_reference<decltype(bar)>::value << std::endl;
  21.     }
  22. };
  23.  
  24. int main()
  25. {
  26.     int i;
  27.     Foo<short> a(i);
  28.     Foo<short> b(4);
  29.     Foo<short> c(std::numeric_limits<long>::max());
  30.  
  31.     // Causes "error: use of deleted function ‘Foo<T>::Foo(R&&, typename std::enable_if"
  32.     //Foo<short> d("failed");
  33.  
  34.     return 0;
  35. }
  36.  
Success #stdin #stdout 0s 2896KB
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Standard input is empty
stdout
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Initialized from rvalue reference: 0
Initialized from rvalue reference: 1
Initialized from rvalue reference: 1
https://ideone.com/qnkQ7P
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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