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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. namespace X
  5. {
  6.     template<typename T> struct Mat { typedef T value_type; };
  7.     template<typename T> struct MatExpr {};
  8.  
  9.     template<typename T>
  10.     MatExpr<T> prod(Mat<T> const& A, Mat<T> const& B) { return MatExpr<T>(); }
  11. }
  12.  
  13. struct Mat2 {};
  14.  
  15. template<typename T>
  16. X::Mat<T> prod(const X::Mat<T> &A, const Mat2 &B) { return X::Mat<T>(); }
  17.  
  18.  
  19. template<typename T1, typename T2>
  20. auto operator *(const T1 &a, const T2 &b) -> decltype(X::prod(a, b))
  21. {
  22. 	cout << __PRETTY_FUNCTION__ << '\n';
  23.     return X::prod(a, b);
  24. }
  25.  
  26. template<typename T1, typename T2>
  27. auto operator *(const T1 &a, const T2 &b) -> decltype(::prod<typename T1::value_type>(a, b))
  28. {
  29. 	cout << __PRETTY_FUNCTION__ << '\n';
  30.     return ::prod(a, b);
  31. }
  32.  
  33. int main()
  34. {
  35. 	X::Mat<int> a, b;
  36. 	a * b;
  37. 	Mat2 c;
  38. 	a * c;
  39. }
  40.  
Success #stdin #stdout 0s 3296KB
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Standard input is empty
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decltype (X::prod(a, b)) operator*(const T1&, const T2&) [with T1 = X::Mat<int>; T2 = X::Mat<int>; decltype (X::prod(a, b)) = X::MatExpr<int>]
decltype (prod<typename T1::value_type>(a, b)) operator*(const T1&, const T2&) [with T1 = X::Mat<int>; T2 = Mat2; decltype (prod<typename T1::value_type>(a, b)) = X::Mat<int>; typename T1::value_type = int]
https://ideone.com/coDGye
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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