Can pure virtual function be Variadic function template？

Question

Can i write a class like this:

class Base {
  template <typename...Args>
  virtual double calculate(const Args&...args) = 0;
};

then i want to write derived class like this:

class Derived1 : public Base {
  double calculate(int a) {
  }
};

class Derived2 : public Base {
  double calculate(int a, int c) {
  }
};

if this is not possible, is there any methods can achieve this?

A possible workaround would be to define a standardized structure for the parameters and rely on polymorphism. Something like [this](https://godbolt.org/z/xofTK9a1P) :) — Fareanor, Mar 24 '21 at 14:30

score 5 · Accepted Answer · edited Mar 24 '21 at 13:42

No. Virtual functions can not be templates at all. That applies to any template (variadic or not), and all virtual functions - pure or not.

If you think about it, it makes sense. Template is not a function, it is a template by which compiler will make a function when it is called. A virtual function, on the other hand, have to be a real function, which compiler calls through function pointer to achieve polymorphic behavior.

Can pure virtual function be Variadic function template？

1 Answers1