How to support 2 versions of an interface in MFC using nested classes

Visual Studio48
Hi,



I have a dialog that will currently supports the IFoo interface. I've

extended this to IFoo2 which inherits from IFoo.



I've added 2 interface map entries to the interface map, 1 for IFoo and

1 for IFoo2. There are 2 nested classes, 1 that implements IFoo and

another that implements IFoo2 (all methods from IFoo + methods from

IFoo2).



The problem I am experiencing is when I attempt to call Foo's methods

through a Foo2 ptr the method failes with the following error code:



0xC0000005



Is this the correct way to implement multiple versions of the same

interface?



Thanks in advance.


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