fork download 
  1. #include <type_traits>
  2.  
  3. struct A { int x; };
  4. struct B { int x; };
  5. struct C { int x; };
  6. struct D { int x; };
  7.  
  8. template <class ... Params> class Parameter { };
  9.  
  10. template <class Param>
  11. class Parameter<Param> : public Param
  12. {
  13. public:
  14.     //! Get a parameter
  15.     template <class Param2>
  16.     typename std::enable_if<std::is_same<Param, Param2>::value, int>::type
  17.     getParam() const
  18.     { return Param::x; }
  19. };
  20.  
  21. template <class Param, class ... Tail>
  22. class Parameter<Param, Tail ...> : public Param, public Parameter<Tail ...>
  23. {
  24. public:
  25.     using Parameter<Tail ...>::getParam;
  26.     //! Get a parameter
  27.     template <class Param2>
  28.     typename std::enable_if<std::is_same<Param, Param2>::value, int>::type
  29.     getParam() const
  30.     { return Param::x; }
  31. };
  32.  
  33. class Base : public Parameter<A, B>
  34. { };
  35.  
  36. class Derived : public Base, public Parameter<C, D>
  37. {
  38. public:
  39.     using Base::getParam;
  40.     using Parameter<C, D>::getParam;
  41. };
  42.  
  43. int main(int const argc, char const * argv[])
  44. {
  45.   Base base;
  46.   int a = base.getParam<A>(); // ok
  47.   int b = base.getParam<B>(); // ok
  48.  
  49.   Derived derived;
  50.   int c0 = derived.getParam<C>();
  51.   int c1 = derived.Derived::getParam<C>();
  52.   int c2 = derived.Parameter<C, D>::getParam<C>();
  53.  
  54.   int a0 = derived.getParam<A>();
  55.   int a1 = derived.Base::getParam<A>();
  56.   int a2 = derived.Parameter<A, B>::getParam<A>();
  57.  
  58.   return 0;
  59. }
  60.  
Success #stdin #stdout 0s 3292KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
https://ideone.com/BbLKxb
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!