Re: Automatically create a clone() function for derived classes
Noah Roberts wrote:
class Clonable {
protected:
template < typename T >
Clonable( T const* t) : pimpl(new impl<T>(t))
{}
Clonable * clone() const { return pimpl->clone(); }
private:
struct impl_base
{
virtual Clonable* clone() const = 0;
};
template < typename T >
struct impl : impl_base
{
impl(T const* t) : var(t) {}
Clonable * clone() const { return new T(var); }
T const* var;
};
scoped_ptr<impl_base> pimpl;
};
Actually, thinking about it more I'm pretty confident that this
interface could be further extended so that the clone functionality
isn't even in the class you're using and you could use ANY inheritance
tree in this manner. This would be the optimal design in many cases.
You would simply implement this as a sort of smart pointer that does
deep-cloning on whatever object it points to. Should be relatively
straightforward to implement using the techniques in the above so I'm
not going to do so here.
What would be really nice is a policy based smart pointer that you could
add this functionality to as a policy. Might look into Loki to see if
it's there already.