Is it possible to describe template from a class method?

Question

C++ / C#

Schematically, the task looks like this: there is a class, for example, this

class A {
public:
  char *f1(int v) {};
  char *f2(int v) {};
}

Is it possible to describe a function that, depending on the template argument, would call the f1() or f2() method?
Something like this:

template <???fname???>
int F(A *a, int b) {
    return a->fname(b);
}

Answer 1

Is it possible to describe a function that, depending on the template argument, would call the f1() or f2() method?

Here is an option with specialization and without additional parameters in the signature:

template <int f>
int F(A *a, int b) {
    abort();
}
template<>
int F<1>(A *a, int b) {
    return a->f1(b);
}
template<>
int F<2>(A *a, int b) {
    return a->f2(b);
}

Answer 2

You can pass a pointer to a class method into a template.

#include <iostream>     // std::cout

struct A 
{
  int f1(int v) {return v * 5;}
  int f2(int v) {return v * 10;}
};

template <typename Foo>
int F(int b, A * a, Foo foo) 
{
    return (a->*foo)(b);
}

int main () 
{

  A * a = new A;
  
  std::cout <<  F(5, a, &A::f1) << '\n';
  std::cout <<  F(10, a, &A::f2) << '\n';

  return 0;
}

cpp.sh/3l5

Answer 3

You cannot pass a function name as an argument.
You can solve this through macros, for example like this . You
can also pass a pointer to a function, but I think it will be a little more gemorno.