“multiple overloads” using templated class with duplicate types

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Category:Languages

I'm trying to write a class that takes two templated types. This class inherits from an interface. See the below code.

#include <iostream> #include <string>  template <typename T> class IObserver {  public:   virtual void Next(const T& value) noexcept = 0; };  template <typename T1, typename T2> class BinaryObserver : public IObserver<T1>, public IObserver<T2> {  public:   void Next(const T1& value) noexcept override{};    void Next(const T2& value) noexcept override{}; };  int main() {   // This is OK   BinaryObserver<int, float> mc1;   mc1.Next(0);   mc1.Next(0.0f);    // This fails to compile with "multiple overloads"   BinaryObserver<int, int> mc2;   mc2.Next(0);   mc2.Next(0); } 

I'm having trouble when T1 is the same type as T2. Obviously this means two Next functions will be generated with the same type, which gives an error: multiple overloads of 'Next' instantiate to the same signature.

What's an idiomatic way of fixing this? I'm not sure how to handle the case when T1=T2 since I'd only need one Next function generated

Thanks!

 


How about a specialization:

template <typename T> class BinaryObserver<T, T> : public IObserver<T> {  public:   void Next(const T & value) noexcept override{}; }; 

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