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  1. #include <string>
  2. #include <iostream>
  3. #include <functional>
  4.  
  5. using namespace std::placeholders;
  6.  
  7. struct overloaded
  8. {
  9.     int operator()(const std::string& s) const { return 1; }
  10.     int operator()(double d)             const { return 2; }
  11. };
  12.  
  13. template <typename T>
  14. auto makefoo(const T& t) -> decltype(std::bind(overloaded(), t))
  15. {
  16.     return std::bind(overloaded(), t);
  17. }
  18.  
  19. int main()
  20. {
  21.     overloaded foo;
  22.  
  23.     // based on local bind expression:
  24.     auto unresolved = std::bind(foo, _1);
  25.     std::cout << unresolved(3.14)   << std::endl;  // should print 2
  26.     std::cout << unresolved("3.14") << std::endl;  // should print 1
  27.  
  28.     // based on a factory function template
  29.     std::cout << makefoo(3.14)()   << std::endl;  // should print 2
  30.     std::cout << makefoo("3.14")() << std::endl;  // should print 1
  31. }
Success #stdin #stdout 0s 2960KB
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https://ideone.com/JILEA
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
secret

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