False warning about name can be not defined in PyCharm

Question

I wrote a python code to give a value to a variable if it is not defined, but nevertheless PyCharm warns me that the variable can be not defined:

if 'TEST' not in globals():
    TEST = "test"

print(TEST)

Name 'TEST' can be not defined

Is there an other way to define undefined variables such that PyCharm understand it?

PyCharm can't really tell that the logic of this ensures that the name must be defined. It only looks at syntax, it can't figured out the implication of the test. — Barmar, Commented May 25, 2018 at 15:00
@Barmar I disagree with this because if I add the statement else: TEST = globals().get('TEST') I get rid of the warning. I think the problem comes more from the fact that we access to the variable via a string, which I find ugly but apparently there is no way to do otherwise. — Jean Paul, Commented May 28, 2018 at 9:20
@JeanPaul It has nothing to do with accessing variable through a string. It gets rid of the warning only because you provided an else block. PyCharm can't understand the logic if 'TEST' not in globals() is False then it is already defined — DeepSpace, Commented May 28, 2018 at 9:39
@JeanPaul Consider this piece of code: x = 1 ; if x == 1: foo = 2 ; print(foo) Here we also get the warning that foo may not be defined even though we hardcoded the condition which defines foo to always be True. Pycharm follows all possible branches according to the syntax, not logically. — DeepSpace, Commented May 28, 2018 at 9:44

ivan_pozdeev · Accepted Answer · 2018-05-25 20:13:57Z

7

You can use a nonconditional initializer, e.g. with get, to get rid of the warning:

TEST = globals().get('TEST', 'test')
print(TEST)

ivan_pozdeev

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answered May 25, 2018 at 14:53

DeepSpace

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3

@Barmar Indeed. However using get will get rid of the warning (and the unnecessary if). I changed the wording a bit.
– DeepSpace
Commented May 25, 2018 at 15:16

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zzcron toby · Accepted Answer · 2020-01-03 14:04:19Z

0

You should ensure that TEST is initialized.

TEST = 'TEST'
if 'TEST' not in globals():
    TEST = "test"
print(TEST)

answered Jan 3, 2020 at 14:04

zzcron toby

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The goal of my code is not to overwrite the TEST variable if it has been previously initialized. Explicitlly initialize it is not a solution for me, and doing so the two lines in the middle are useless.
– Jean Paul
Commented Jan 14, 2020 at 15:39

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2 Answers 2