order of base class declaration

[Sandeep Pulla]

Can anyone shed light on why the following gives the compile time
error:

'entity *surface_entity::clone(void)' : overloaded member function not
found in 'surface_entity'

=========================================================================
class entity {
public:
virtual entity* clone() const = 0;
};

class surface {
protected:
virtual void redo_caches() const {}
};

class surface_entity : public surface, public entity {
public:
surface_entity* clone() const { return new surface_entity(*this); }
private:
void redo_caches() const {}
};
=========================================================================

Whereas either

[a] Making either "clone()" OR "redo_caches()" non-virtual

or

Changing the order of base class declaration, i.e., "public
entity, public surface" instead of "public surface, public entity"

makes the error go away?


Thanks in advance,
Sandeep

p.s. the compiler is microsoft visual c++ 7

 

[Ron Natalie]

Can anyone shed light on why the following gives the compile time
error:

'entity *surface_entity::clone(void)' : overloaded member function not
found in 'surface_entity'

Most likely that your compiler doesn't implement covariant return types.
Try defining surface_entity::clone() to return entity*.

p.s. the compiler is microsoft visual c++ 7

Try asking in microsoft.public.vc.language. They're more familiar with VC++'s
bugs and limitations there.