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pythonrepeatpython-2to3

Python 2to3 warning <You should use 'operator.mul(None)' here.> What does it mean?

I am using 2to3 to convert a script. The only warning I get is:

RefactoringTool: Line 716: You should use 'operator.mul(None)' here.

Line 716 of the original script is:

classes = repeat(None)

I don't get where shall I use operator.mul(None). The reference documentation of repeat() (link to docs) shows that I can pass None without any problem. So, what shall I do?

Solution

  • 2to3 is just getting confused about which repeat you mean. It thinks you're using operator.repeat in Python 2:

    Help on built-in function repeat in module operator:

repeat(...)
    repeat(a, b) -- Return a * b, where a is a sequence, and b is an integer.

    instead of itertools.repeat. That's not a great guess on its part, to be honest, because operator.repeat takes 2 arguments, but that's what it's guessing. You can see the transformation listed in the docs.

    You can avoid the warning by using the fully-qualified itertools.repeat or just ignore it.