Re: C++ language: Cloneable cl*****

On 7 Maj, 02:43, Daniel Krügler <daniel.krueg...@[EMAIL PROTECTED]
>
wrote:
> Probably you meant a const version of this:
> virtual A* doClone() const { return new A( *this ); }

That's right, of course..

> "If the return type of D::f differs from the return type of
> B::f, the class type in the return type of D::f shall be
> complete at the point of declaration of D::f or shall be the
> class type D."
>
> In your example, Derived is incomplete at this point and
> different from Cloneable.

I see. This explains everything, thanks. So I need a workaround..

> #include <memory>
>
> class CloneableBase
> {
> public:
>      virtual ~CloneableBase() {}
> protected:
>      virtual CloneableBase* doClone() const = 0;
>
> };
>
> template < typename Derived>
> class Cloneable : public CloneableBase
> {
> public:
>      typedef std::auto_ptr<Derived> AutoPtr;
>      AutoPtr clone() const {
>        return AutoPtr( static_cast<Derived*>(this->doClone()) );
>      }
>
> };

Yes, I implemented a similar solution in my code, but until now, I
considered it a tem****ary workaround.. I now see, that it's the final
solution, thanks.


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