[python-win32] Python COM Server, C++ Client - How ??? (multiple arguments)

[Mark Hammond]

> For posterity ...
> 
> I posted a recepie a while ago on how to write a simple C++
> client for a Python com server.
> 
> FYI to handle a COM method that has more than 1 argument, for some
> reason you
> have to reverse the order of arguments.
> 
> For example, if the method is defined
> 
> def my_method(self, a,b,c,d):
>  ...
> 
> Then your C++ client should look like :
> 
> 	vargs[0]=arg4;
> 	vargs[1]=arg3;
> 	vargs[2]=arg2;
> 	vargs[3]=arg1;
> 
> 	dp.rgvarg=vargs;
> 	dp.cArgs = 4; //how many args
> 
> Where 'arg4' is the *last* argument ('d') (place it at array index 0
> rather
> than 3).
> 
> Don't know why.

This is how IDispatch is documented to behave - eg, see
http://msdn2.microsoft.com/en-us/library/ms221653.aspx - "The arguments in
the array should be placed from last to first, so rgvarg[0] has the last
argument and rgvarg[cArgs -1] has the first argument."  On a somewhat
related note, pywin32 recently had a bug where 'named params' would be
reversed when passed to python code, and while this fix will appear in build
211, it doesn't relate directly to your observation.

Cheers,

Mark