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  1. #include <iostream>
  2. #include <string>
  3.  
  4. using namespace std;
  5.  
  6. template <typename T>
  7. class Base {
  8. public:
  9.     Base(const T& t) : _t(t) {}
  10.     virtual ~Base() { }
  11.  
  12.     void doSomething() { cout << "Hello world\n"; }
  13.  
  14.     virtual T getVal() const { return _t; }
  15.  
  16. private:
  17.     T _t;
  18. };
  19.  
  20. class DerivedA : public virtual Base<string>
  21. {
  22. public:
  23.     DerivedA(const string& path) : Base<string>(path) {}
  24.     virtual ~DerivedA() {}
  25. };
  26.  
  27. namespace details {
  28.     template<typename T>
  29.     Base<T>* make_base(Base<T>* param) { return param; }
  30. }
  31.  
  32. template<typename T>
  33. auto make_base(T& param) -> decltype(details::make_base(&param)) { return details::make_base(&param); }
  34.  
  35. int main() {
  36.   DerivedA foo("foo"s);
  37.   auto bar = make_base(foo);
  38.  
  39.   bar->doSomething();
  40. }
Success #stdin #stdout 0s 15240KB
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Standard input is empty
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Hello world
https://ideone.com/3kr0VZ
language:
C++ (gcc 8.3)
created:
7 years ago
visibility:
public

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