Problems with inheritance (and factory functions).

[Rocco Rossi]

Hi all.

I've had this sort of problem on different occasions and totally different
circumstances.
Here it is:

In the first case I needed to write a Partlcle class (for solving physics
problems), and I did it pretty
easily enough. Now I included in this class all the methods (and some
operator methods) I needed, and that worked very nicely too.

The problem came up when I tried to specialize my class by inheritance. I
wanted to create a Spin-Particle class
which had a member variable representing the "spin" value of the particle
(1/2, 1, etc.). I found out that some
of the methods which were inherited from the super-class continued
(obviously!) to return values of Particle type
which wasn't what I wanted. I needed them to adjust accordingly and return
values of the new type, but of course this
wasn't possible.

I had this same problem another time although the situation was very
different. I wanted to create my own MySocket class
inheriting from the well-known library Socket class, and all I wanted was to
add some specialized methods of mine to accomplish some specific tasks. I
found out though that the "connect" method in the base class Socket creates
new instances
of Socket type, and of course that is exactly what was going on with the
MySocket class too, so basically every time I
succeeded in making a connection what I got was new instances of Socket type
which had none of the new methods that I
added and wanted in the first place.

Is there some solution (design pattern) that can overcome problems like this
one???

Thanks.

Rock