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  1. #include <iostream>
  2. #include <functional>
  3.  
  4. int foo(int i)
  5. {
  6.     return i*2;
  7. }
  8.  
  9. template <typename Ax, typename R, typename... A>
  10. struct Wrap
  11. {
  12.     typedef R (*F)(A...);
  13.     typedef std::function<R(A...)> Ftor;
  14.  
  15.     Wrap(F f) : _f(f) { }
  16.     Wrap(const Ftor& f) : _f(f) { }
  17.  
  18.     R operator()(Ax extra, A... a) const
  19.     { return _f(a...); /*just forward*/ }
  20.  
  21.     Ftor _f;
  22. };
  23.  
  24. template <typename Ax=int, typename R, typename... A>
  25. std::function<R(Ax, A...)> wrap(R (f)(A...))
  26. {
  27.     return Wrap<Ax,R,A...>(f);
  28. }
  29.  
  30. template <typename Ax=int, typename R, typename... A>
  31. std::function<R(Ax, A...)> wrap(std::function<R(A...)> functor)
  32. {
  33.     return Wrap<Ax,R,A...>(functor);
  34. }
  35.  
  36. int main(int argc, const char *argv[])
  37. {
  38.     auto bar = wrap(foo);
  39.     std::function<int(int, int)> barfunc = wrap(foo);
  40.  
  41.     std::cout << barfunc(-999, 21) << std::endl;
  42.  
  43.     // wrap the barfunc?
  44.     auto rewrap = wrap(barfunc);
  45.     std::cout << rewrap(-999, -999, 21) << std::endl;
  46.  
  47.     return 0;
  48. }
  49.  
Success #stdin #stdout 0s 2964KB
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https://ideone.com/8KIsW
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
secret

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