Re: [boost] Re: [BGL] MutablePropertyGraph questions

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-02-03 01:40:25

Chris Russell wrote:
> Let me first describe my heterogeneous container hack and perhaps you could
> point why it's poor (your feel better on a quick read of your paper and this
> is a good way to help us all understand this a bit better).
> 
> My goal was to be able to use standard STL containers and iterators with
> heterogeneous collections of objects. My hack was to declare a class
> CMoniker that takes a pointer to some CMonikerBase-derived class through a
> templated constructor. This constructor does two things: it casts the
> pointer to a void * and stores it in a private member. Additionally it uses
> RTTI to record the type. CMonikerBase is invasive; it provides reference
> counting for the object and operator overloads for STL containers. Any class
> that derives from CMonikerBase can then be stuffed into a CMoniker, and I
> then use the standard STL containers/iterators to work with homogenous
> collections. A CMoniker has a templated operator: template <typename Type>
> operator Type&() that internally uses RTTI to test Type and throw an
> exception if it doesn't match the internal type squirreled away in the
> constructor. Ugly - yes. The filtering operation you propose in your paper
> is similar to little helper classes I write to enumerate elements in my
> some_stl_container<CMoniker> to produce another container full of objects of
> a given type - again this is inelegant but it does seem to work.

I'm probably wrong, but it looks like boost::any. I can't tell a difference, 
at least.

- Volodya