Sandbox/VariadicUsing.cpp

   1 #include "VariadicUsing.h"
   2
   3 #include <iostream>
   4 using namespace std;
   5
   6 // Ep 48: https://www.youtube.com/watch?v=1gNzhE-Tn40
   7
   8 namespace VariadicUsing
   9 {
  10     template<typename ... B>
  11     struct Merged : B...
  12     {
  13         template<typename ... T>
  14         Merged(T&& ... t) : B(forward<T>(t))...
  15         {
  16         }
  17
  18         using B::operator()...; // It seems not necessary.
  19     };
  20
  21     // Class template argument deduction: https://en.cppreference.com/w/cpp/language/class_template_argument_deduction.
  22     template<typename ... T>
  23     Merged(T...) -> Merged<decay_t<T>...>;
  24 }
  25
  26 void VariadicUsing::tests()
  27 {
  28     // Lambda are standard type.
  29     const auto l1 = []() { return 4; };
  30     const auto l2 = [](const int i) { return i * 10; };
  31
  32     Merged merged(l1, l2, [](const double d) { return d * 3.2; });
  33
  34     cout << merged() << endl;
  35     cout << merged(10) << endl;
  36     cout << merged(10.5) << endl;
  37 }