mixing templates with polymorphism

Question

class A
{
    friend void foo();
    virtual void print_Var() const{};

};// does not contain variable Var;


template
class B : public A
{
    T Var;         


        

Answer 1

I think it will be the easiest way. Just move the comparison method to the interface and override it in derived classes. Add the following lines to yor example:

class A
{
   /*..................................................*/
   virtual bool comp(const int) const { return false; }
   virtual bool comp(const std::string) const { return false; }
   virtual bool comp(const double) const { return false; }  
};

template
class B : public A
{
   /*..................................................*/
   virtual bool comp(const T othr) const override { return othr == Var; }
};

void foo()
{
      /*..................................................*/
      if (i->comp(20))
      {
         /* do something*/
      }

      if (i->comp("Hello Stackoverflow"))
      {
         /* do something*/
      }
      /*..................................................*/
}