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