Attached patch turns the Python implementation of functools.partial into a class. The implementation is as close to the C version as possible, except __repr__ where I went for a different, more Pythonic approach (output is identical).

I haven't yet added tests for this, and I had to fix something (because some errors occur if _functools is not present and that's the only way I know to make the tests run against the Python implementation). One test fails with the patch (and sys.modules["_functools"] = None):

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ERROR: test_pickle (test.test_functools.TestPartialC)
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Traceback (most recent call last):
  File "E:\GitHub\cpython\lib\test\test_functools.py", line 224, in test_pickle
    f_copy = pickle.loads(pickle.dumps(f, proto))
_pickle.PicklingError: Can't pickle <class 'functools.partial'>: it's not the sa
me object as functools.partial

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Ran 148 tests in 0.216s

FAILED (errors=1)

I'll try to see what kind of tests I can add to this to reliably test both 'partial' implementations. I'll also see what I can do about that one failing test. Oddly enough, there seems to be a test for subclassing '_functools.partial', which I might extend.

Raymond, what do you think?