Boost::Bind and virtual function overloads: why do they work?

Question

I wrote some code and got scared that it will not work - so I wrote a prototype:

#include 
#include 
#include         


        

Answer 1

A pointer to a virtual method does a virtual function lookup when called.

#include 
#include 

struct base {
  virtual void foo() { std::cout << "base\n"; }
  virtual ~base() {}
};

struct derived:base {
  void foo() override final { std::cout << "derived\n"; }
};

int main() {
  void (base::*mem_ptr)() = &base::foo;
  std::unique_ptr d( new derived() );
  base* b = d.get();
  (b->*mem_ptr)();
}

so, it "just works". The member function pointer (this->*&base::foo)() is not the same as a fully qualified function call this->base::foo(). The first is a way to store the foo part of calling this->foo(), the second is a way to skip virtual method lookup and directly call base::foo.