new and polymorphism

[Elrond]

Hi,

I am doing too much coding with MFC, thus I have kind of forgotten some real object coding with C++. I have a little question about polymorphism with the new operator:

Say I have these three classes:

class A {...}; //this is a pure virtual class
class A1: public A {...};
class A2 : public A {...};

I want to do something like this:

BOOL my_function(A param)
{
    //A* m_pA
    m_pA = new ???;
    *m_pA = param;
}

I don't know before hand what derived type of A the parameter will be, but I must create a new object of this type. The definitions of the classes have no real importance. The only solution I have so far is to have an attribute in A that gives the sub type (initialized in the Ctor, cannot be modified). Then I check on this type to make the proper new:

switch( param.type)
{
case type_1: m_pA = new A1; break;
case type_2: m_pA = new A2; break;
}

What's the "correct or best" "OO or C++" solution for that?

I would have another solution using a static function as an object factory...