Re: [boost] [smart ptr] Any interest in copy-on-write pointer for C++11?

Subject: Re: [boost] [smart ptr] Any interest in copy-on-write pointer for C++11?
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2013-02-08 16:33:41

On 08/02/13 18:52, Ralph Tandetzky wrote:

> It wouldn't work to add the cow logic on top of a shared_ptr, when
> polymorphism is involved. Then an explicit clone() member function of
> the template type would be needed. The nice thing about the cow_ptr is
> that you can get this cloning facility non-intrusively.

I don't see how doing that while using shared_ptr is a problem.
Either you make a shared_ptr of your structure that contains your 
cloning thing, or you store it separately.
Of course you'll need to change the virtual function declaration to T* 
clone(T*), since the structure wouldn't contain the object anymore.

Storing it separately seems like a better idea since it avoids the 
unneeded use of dynamic allocation (all derived types are the same size).