Re: [boost] [smart pointers] Proposal to add some small utilities

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-11-21 20:07:36

Ion Gaztañaga wrote:

[...]

> While developing pointer-independent code, however,
> I've seen that some features are present in boost (for example,
> get_pointer() function) and other features are missing, and I would
> like to propose them:
>
> 1. Overloads of static_pointer_cast, dynamic_pointer_cast,
> const_pointer_cast overloads for raw pointers, so that we can use
> pointer_xxx_cast in a generic way.

Makes sense. :-) boost/utility/pointer_cast.hpp, probably.

> 2. Add reinterpret_pointer_cast to complete cast family.

Out of curiosity, why do you want it?

> 3. A protocol to obtain a pointer of the same type from any pointer.
> For example, if you want to generically use a pointer (for example,
> raw or relative pointer) in a class and you want to declare another
> pointer to other type (raw or relative, depending on the source):
>
> //typedef typename boost::pointer_to_other
> //<GenericPointer, NewType>::type MyNewPointer;
>
> //A new pointer to float values
> typedef typename boost::pointer_to_other
>    <SmartPtr, float>::type MyFloatPointer;
>
> We should define how this protocol is implemented in boost smart
> pointers (for example, using overloading or a STL-like rebind mechanism)
> so that every boost smart pointer developer knows how to make its
> pointer type protocol-aware.

template<class T, class U, template<class> class Sp>
    class pointer_to_other< Sp<T>, U >
    {
        typedef Sp<U> type;
    };

works with auto_ptr and all boost smart pointers. Other smart pointers may 
want to specialize pointer_to_other.