Parameter-less COM method would give "TypeError: x.y takes 1 positional argument but 2 were given", for Delphi and MFC COM clients.

[wxinix]

When calling from a Delphi client (or MFC C++ client), parameter-less COM method would give "TypeError: xxxxx takes 1 positional argument but 2 were given"

This is because:

• When calling from a Delphi client while the target Python method has NO argument (i.e., taking only "self"), arg[0] will be set by Delphi a value of 0x8002000C. This makes args non-empty.

• When calling from a C++ MFC/COM client while the target Python method has NO argument (i.e., talking only "self"), arg[0] will be set a value of "None". This makes args non-empty.

The following code would be a "protection" for parameter-less Python COM method.

import inspect
argspec = inspect.getfullargspec(func).args
if len(argspec) == 1 and argspec[0] == "self":
    return func()
else:
    return func(*args)

Here is a sample Delphi project for replicating the issue. https://github.com/wxinix/Python-COM-Samples/blob/main/Delphi/PythonComDelphiTest.7z

• The Python COM server is defined in "MyCOMServer.py" file, including with the Delphi project files. Register the COM server first.
• Compile and run Delphi, click the "Test Python COM" button

[mhammond]

0x8002000C == DISP_E_UNKNOWNLCID - so it sounds like something else is is going wrong with the arg passing. I don't have delphi - is this possible to repro anywhere else? I'm a bit reluctant to take a hack to work around one environment I can't test until I'm very sure it isn't going to break any other environment where things work perfectly well.

[wxinix]

I further tested clients in Delphi, C++/ATL, and C#. Only Delphi client has the issue. C# and C++ have no problem. https://github.com/wxinix/pywin32-samples

I believe the bug is really Delphi's, and should be resolved on Delphi side. I am going close this issue. How can I withdraw the PR, or you can feel free to reject it.

Thank you for your great efforts on pywin32. The more I look into its source code, the more I feel awe about it. COM still alive!