Inheritance problem

[Andersson]

Hi,

I have an abstract base class - let's call it MyInterface - and a class that most classes in my program inherit from, let's call it MyBaseclass.

Let's assume that all my objects inherit MyBaseclass, some of which also inherit MyInterface. Now I want to collect objects in a container class, MyContainerclass. The container class is only interested in objects that implement MyInterface.

Now I know that all objects that inherit MyInterface also inherit MyBaseclass, but the compiler doesn't know that. MyContainerclass wants to call methods in MyBaseclass, but it collects pointers to MyInterface classes. I can't make MyInterface inherit MyBaseclass, because I will be using classes that I don't want to change (they are part of a framework) that already inherit MyContainerclass. IOW, I can't use virtual inheritance to get a nice inheritance diamond.

To sum up, I want to create a container class that:
1. Collects objects that implement MyInterface.
2. Calls MyBaseclass methods on the collected objects.

I'm not sure how to solve this... I'd appreciate any help.

Thanks in advance!

[MiiNiPaa]

Use duck typing with templates.

Or make your container accept objects of MyBaseClass. As all your objects inheriting from MyInterface inherits from MyBaseClass too, it should accomodate all of them.

[Andersson]

Your comment made me start thinking in a new direction, I've solved it now (and quickly, once I started to get it). Thank you!