Re: [boost] Performance comparison between ptr_vector and vector<cow_ptr<Shape> >, vector<copy_ptr<Shape> >

From: Thorsten Ottosen (tottosen_at_[hidden])
Date: 2006-01-05 15:58:21

Thorsten Ottosen wrote:
> Sam Partington wrote:

>>It seems to me that the first has the disadvantage of making it
>>relatively easy to provide an incorrect cloner that allows slicing. 
>>However this is relatively easy to avoid by making your hierarchy
>>noncopyable, (Perhaps a way around this is to remove the default
>>implementation of new_clone?)
> 
> 
> It's not very sensible to make the hierarchy copyable, because you
> can run into slicing in other places then.
> 
> As for the default, then I've been thinking about this too. It still 
> won't catch that one missed a clone() function longer down the hiararchy.
> 

Hm...I just came to think that a little assertion might help us out here:

inline base* new_clone( const base& b )
{
        base* res = b.clone();
        assert( typeid(*res) == typeid(b) );
        return res;
}

That should catch any problems. I can even put this inside the 
clone-allocator, so the user don't have to specify this.

-Thorsten