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importhook.cs breaks python's import interface #1245
Description
Environment
- Pythonnet version: 2.5.1
- Python version: 3.7.9
- Operating System: Windows 10
Details
- Describe what you were trying to get done.
pythonnet overwrites the python's __import__ routine, but does not implement python's signature precisely:
original python's signature is
__import__(name, globals=None, locals=None, fromlist=(), level=0)Most other python modules call the name parameter as positional: __import__("foo", ...
Some packages (e.g. kivy) use __import__ as
__import__(
name='{2}.{0}.{1}'.format(basemodule, modulename, base),
globals=globals(), locals=locals(), fromlist=[modulename], level=0
)i.e. the name argument used as keyword argument in the call. Both calls are valid in python's __import__, but fail at the overwritten __import__ with
TypeError: __import__() takes at least 1 argument (0 given)A hotfix is to alter the other modules code to
__import__(
'{2}.{0}.{1}'.format(basemodule, modulename, base),
globals=globals(), locals=locals(), fromlist=[modulename], level=0
)but the broken code is within pythonnet.
Activity
SStarosielec commented on Oct 5, 2020
I'm not sure this section from https://docs.python.org/3/reference/expressions.html#calls applies (I don't understand all the lingo):
It then seems an incompatibiliy between python anc CPython, should CPython be fixed instead ?
filmor commented on Oct 5, 2020
This should be relatively easy to fix and PRs are welcome, thank you for looking into this in detail (was reported before in #547).
The error here is partially on Kivy for calling __import__ directly instead of using importlib, and as you quoted we are kind-of allowed to make __import__ behave in this way.
Mid-term (hopefully in pythonnet 3), this should not be a problem anymore by implementing proper PEP302-style importing instead of overriding __import__.