[python-win32] extending com objects

[Tim Golden]

[Tim Golden]
>> Presumably, then, if the original COM class exposed,
>> say, a .GetGroups method which returned a list of
>> groups, each of which you wanted to wrap, in this
>> implementation, you'd add a .MyGetGroups method which
>> called the original and wrapped the result?

[Ross McKerchar]
> It's simpler than that: as long as you've monkey-patched the original 
> COM groups class, the groups returned by the GetGroups method will 
> already have your methods: no need to wrap.

I see what you mean. As you say, this assumes they're
already "victims" of your patching, but I imagine this
is usually the case.

[Ross McKerchar]
> 1) Using your own attributes gets tricky as they pythoncom tries to 
> automatically assign them to the underlying com object. I've been 
> bypassing the __setattr__ override by doing "self.__dict__['spam'] = 
> 'ham'" which would could get tedious rather quickly...

You could -- probably -- define a __setattribute__ method,
but that would only work if the pywin32-generated classes
were new-style (and I doubt they are).

> 2) Defining your own __init__ causes all sorts of problems :)
> 
> 3) You "take over" the com classes: that is, comclass.__class__ is your 
> class, not the original com_class: any kind on explicit introspection 
> (isinstance, etc.), within pythoncom or existing client code could now 
> fail. Again a less naive patching process that didn't overwrite 
> everything blindly should be easy.

As you say. Well for the kind of modules I find myself
churning out, this looks like an interesting approach,
so do report back with pitfalls or... whatever the
opposite of pitfalls is!

TJG