[boost] proposed extension for boost::any

24 Feb 2005

      Hi all,

    While using boost::any with pointers, I realized the following 
problem for polymorphic classes:

\code
  class A {
  public:
    virtual ~A() {}
  } ;

  class B: public A {} ;

  int main() {
    boost::any b(new B) ;
    try {
      A* a = boost::any_cast<A*>(b) ;
    }
    catch (const boost::bad_any_cast&) {/*failed*/}
  }
\endcode

Of course the following code failes, since rtti information is used for 
casting.

I extended the boost::any concept, and incorporated a 
boost::any_dynamic_cast (see attachment)
This extension uses  boost::is_polymorphic and boost::remove_pointer, 
and allows dynamic casting
if possible.

Does anyone need this features, and can it be incorporated (after some 
regression tests) into the boost::any library?

Thanks for any comment about it.

--Frantz Maerten