Question

I’m trying to subclass a class with a specialisation of how I want a particular function to be performed. However, C++ implicitly converts my class to its base class when I store it in a list. Clearly the list could store any subclass of the class, so this is acceptable, but how would I go about storing the class so I can access this particular function.

The only way I can think of doing this is to use templates, are there any other options?

Here is an example:

class A
{
    A() {}
    virtual void function()
    {
    }
}

class B : public A
{
    B() {}
    void function()
    {
    }
}

boost::shared_ptr<B> b = boost::shared_ptr<B>(new b);
std::list<boost::shared_ptr<A> > objects;
objects.push_back(b);

// pull t out of objects

t.function();

Edit: Oversimplified this, so I’ve fixed a few things…

Answer 1

This is a phenomenon called slicing. The answer is to store a container of pointers instead, such as std::list<A*>. Just remember to delete everything when you’re done.

If you can use the Boost libraries, there is a great library called Pointer Container which helps with this procedure.