How to generate a non-const method from a const method?

Question

While striving for const-correctness, I often find myself writing code such as this

class Bar;

class Foo {
public:
  const Bar* bar() const { /* code that gets          


        

Answer 1

The answer I came up with myself after bending my mind a bit. However, I think I can improve it using the ideas from litb's answer, which I'll post later. So my solution so far looks like this:

class ConstOverloadAdapter {
protected:

  // methods returning pointers 

  template< 
    typename R, 
    typename T >
  R* ConstOverload(
    const R* (T::*mf)(void) const) {
      return const_cast< R* >(
        (static_cast< const T* >(this)->*mf)());
    }

  // and similar templates for methods with parameters 
  // and/or returning references or void
};

class Bar;

class Foo : public ConstOverloadAdapter {
public:
  const Bar* bar() const { 
    /* implementation */ }

  Bar* bar(void* = 0) {  // the dummy void* is only needed for msvc
                         // since it cannot distinguish method overloads
                         // based on cv-type. Not needed for gcc or comeau.
    return ConstOverload(&Foo::bar); }
};