(Best alternative to) Class inheritance in VBA

I grasp at the conceptual level what you want to do, but I think there are a couple of issues in your code example. Also, you need to decide if you want to truly emulate inheritance, or just get the job done in an easy way.

First, in your example, Property must be Get, Let, or Set. I think you need this:

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Secondly, allowing the caller to retrieve the original object breaks the abstraction you are trying to create. That can work but exposes to the caller that you have the original object, plus a bunch of stuff you have added. Plus, from the caller's standpoint, there is no guarantee that operating on that object will continue to be reflected in the extended object. To truly replicate inheritance, you would have to code every property and method of the original, and not allow access to the underlying object. Otherwise the caller has to know when it's dealing with your extended class vs. the original class. If you hide the original object, then the caller does not have to go through the extra step of retrieving the original object, and operating on that. However, this requires writing a method and property for every method and property in the original class (which normally inheritance would do for you under the covers).

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Further, as to your example, it is not clear how you can reference a non-existent method or property in the WebDr object:

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I think you would need something like this to create a new method, which references available methods/properties:

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or something like this which creates a new property:

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I have not used the Implements statement so I would have to study that.

I don't think there is any way to automatically check that your have implemented every property and method. Let me look into it and see what I can come up with.

However, the lack of a language mechanism for inheritance in VBA (much less multiple inheritance, or the Interface feature from Java) makes pure OOP very much a rompicoglioni.