Re: [Boost-users] 'is_pointer_like' or 'is_smart_pointer' orsimilar, again

From: Gottlob Frege (gottlobfrege_at_[hidden])
Date: 2007-01-28 21:55:21

On 1/27/07, Tobias Schwinger <tschwinger_at_[hidden]> wrote:
> Ovanes Markarian wrote:
> > Just a small addition. You can also specialize the template in another
> > file, that is seen in the translation unit.
>
> Be aware, however, that it's not necessarily a good idea:
>
> If you forget to #include the specialization definition, an
> instantiation of is_pointer_like<T>::value can be both 'false' and
> 'true' in the same program. This scenario can lead to strange effects
> that are not necessarily caught at compile time.
>
> You should at least add a forward declaration of the class template
> specialization to the header defining the smart pointer (but you might
> as well just define the specialization in this case because it's trivial).
>
> Regards,
> Tobias
>

I think, at the end of the day, that it would be nice if smart ptrs
derived from some tag classes describing their traits, just like
iterators, containers, unary/binary functions, etc should/do.

ie smart_ptr_tag, weak_ptr_tag, etc.

Tony