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  1. //Refer to: http://m...content-available-to-author-only...y.com/2013/06/03/overriding-the-broken-universal-reference-t/
  2. #include <iostream>
  3. #include <type_traits>
  4.  
  5. template<typename T>
  6. struct class_tag { };
  7.  
  8. template<typename TF>
  9. void apply( TF && f ) {
  10.     //get the unqualified type for the purpose of tagging
  11. 	class_tag<typename std::decay<TF>::type> tag;
  12. 	apply_impl( std::forward<TF>(f), tag );
  13. }
  14.  
  15. template<typename TF, typename Tag>
  16. void apply_impl( TF && f, Tag ) {
  17.  	std::cout << f << std::endl;
  18.  }
  19.  
  20. struct match_a { };
  21. template<typename TF> 
  22. void apply_impl( TF && f, class_tag<match_a> ) {
  23. 	std::cout << "match_a" << std::endl;
  24. }
  25.  
  26. struct match_b { };
  27. template<typename TF>
  28. void apply_impl( TF && f, class_tag<match_b> ) {
  29. 	std::cout << "match_b" << std::endl;
  30. }
  31.  
  32. template<typename TF>
  33. void apply_impl( TF && f, class_tag<int*> ) {
  34. 	std::cout << "int*" << std::endl;
  35. }
  36.  
  37. int main() {	
  38. 	apply( 12 );
  39. 	apply( "hello" );
  40. 	apply( match_a() );
  41. 	apply( match_b() );
  42.  
  43. 	match_a a;
  44. 	apply(a);
  45. 	apply( static_cast<match_a const&>(a) );
  46. 	apply( static_cast<match_a const>(a) );
  47.  
  48. 	int b[5];
  49. 	apply(b);
  50. 	apply(static_cast<int*>(b));
  51. }
  52.  
Success #stdin #stdout 0s 2896KB
comments (?)
stdin
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Standard input is empty
stdout
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12
hello
match_a
match_b
match_a
match_a
match_a
int*
int*
https://ideone.com/s2j1o1
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
secret

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