Re: Design question

"Igor Tandetnik" <>
Fri, 9 Mar 2007 11:26:11 -0500
Alexander Adam <> wrote:

I got an internal set of CPP Klasses, like the following sample:

class A
   B* getB() { return new B(); }
   void doSomethingWithB(B* in) { ... }

class B {..}

Now internally I am working with those classes but need to expose the
whole CPP Hierarchy into COM to use by scripting. I have a custom
IDispatchEx implementation to which I could expose methods to. The
biggest pain I have right now is that I of course cannot pass CPP
Class pointers around my COM objects.

Normally, you would wrap each of your classes in a separate COM object.
So you would have ComA and ComB, wrapping A and B. ComA::getB would call
A::getB, wrap the resulting B object in an instance of ComB, and return
an interface pointer implemented by the latter.

Each wrapper can also implement a private interface, e.g. IRawObject
with a method void* GetRawObject(), returning a pointer to the wrapped
class. For example, ComA::doSomethingWithB will accept an IDispatch
pointer (necessary to be callable by script). It would query it for
IRawObject, call GetRawObject and cast it to B*, then call
A::doSomethingWithB with this pointer.
With best wishes,
    Igor Tandetnik

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