Multiple subtyping with alias this and nested classes

[Sergey Gromov]

Sun, 04 Oct 2009 00:10:30 +0200, Yigal Chripun wrote:

> > interface IBlipper
> > {
> >     void blip();
> >     void nameCollision();
> > }
> > template Blipper()
> > {
> >     void blip() {}
> >     void nameCollision() {}
> > }
> >
> > interface IFlipper
> > {
> >     void flip();
> >      void nameCollision();
> > }
> > template Flipper()
> > {
> >     void flip() {}
> >     void nameCollision() {}
> > }
> 
> interfaces implement virtual MI, so FlippingBlipper must implement one 
> nameCollision which is shared by both interfaces.

That's not correct if you're talking about virtual MI in C++.  There,
you'd have to create a common root for the virtual inheritance to
actually work:

class INameCollider
{
public:
    virtual void nameCollision() = 0;
};

class IFlipper: public virtual INameCollider
{
public:
    virtual void flip() = 0;
};

class IBlipper: public virtual INameCollider
{
public:
    virtual void blip() = 0;
};

class FlippingBlipper: public IFlipper, public IBlipper
{
public:
    // Contains single, common nameCollision()
    virtual void nameCollision() {}
    virtual void flip() {}
    virtual void blip() {}
};

Otherwise, if IFlipper and IBlipper are unrelated, you have two separate
nameCollision() functions which you must disambiguate as
IFlipper::nameCollision() and IBlipper::nameCollision() both when
defining and when calling via a FlippingBlipper instance.