msi automation IDL parameter names

Robert Shearman rob at
Fri May 4 11:23:20 CDT 2007

Misha Koshelev wrote:
> So I am thinking of implementing some more OLE automation functions and
> just wanted to clarify one thing before I start doing this.
> Specifically, parameter names can be arbitrary as far as OLE automation
> in general is concerned, however for MSI in particular when you use the
> incorrect parameters for a method/property (for example one instead of
> two) it throws an exception whose description is
> "Methodname,Param1Name,Param2Name,etc". I had to make a todo_wine in my
> conformance test in this because our parameter names are currently
> different (intentionally as per instructions reference above).
> I doubt that any application would depend on the exact description of
> such an exception, but nonetheless it might be confusing to get
> different parameter names, say, for a developer who is making an MSI (on
> Wine???) and is trying to debug his MSI script. In any case, I doubt it
> matters much but I just wanted to make sure if we should stick with
> using different parameter names or switch to the same ones (I don't know
> what kind of copyright issues this really raises or avoids). Otherwise,
> it would be a pain to change this later on if we already have everything
> implemented and we find that it is necessary to have the same exception
> string for some reason.

Actually, I forgot that with typelibs parameter names are part of the 
For example, in some scripting languages (including VBScript and JScript 
I think) you can do the following:

Methodname(Param1Name=1, Param2Name=2)

This obviously won't work if the parameter names are different.

However, the procedure to cleanly implement an IDL file with compatible 
parameter names isn't clear to me. I would think we would need legal 
advice as to how to do this.

Rob Shearman

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