Pylint warning: Possible unbalanced tuple unpacking with sequence

Question

I have a piece of Python code:

def func1():                                                                                                                  
    a=set()
    b = ','.join(map(str, list(a)))
    return  b, []

def func2():
    d = 1
    e = 2
    return func1() + (d, e,)

def main():
    a,b,c,d = func2()

if __name__ == '__main__':
    main()

When I run it through pylint (1.4.0), I receive the warning:

W: 12, 4: Possible unbalanced tuple unpacking with sequence: left side has 4 label(s), right side has 3 value(s) (unbalanced-tuple-unpacking)

It seems that func2 will always return four results. What does the error mean and why?

It says *possible* (and `W` is just a **w**arning). Evidently the introspection isn't deep enough to determine that `func1` always returns a two-tuple, and therefore that `func2` always returns a four-tuple. Given that you know it isn't a problem, you could add `# pylint: disable=unbalanced-tuple-unpacking` to the offending line. — jonrsharpe, Jan 16 '15 at 08:48
this sounds like a false-positive that should be reported on pylint's issue tracker (https://bitucket.org/logilab/pylint/issues) — sthenault, Jan 16 '15 at 13:59

score 20 · Answer 1 · edited Aug 23 '19 at 17:26

20

If the warning is erroneous, it can be disabled by appending # pylint: disable=unbalanced-tuple-unpacking to the line.

edited Aug 23 '19 at 17:26

Asclepius

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answered Feb 28 '19 at 20:00

The Chess Guy 20

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It worked for me when added before the line with the warning, not after. – Ameer Taweel Jul 05 '19 at 19:09
Ameer, yep, "append" means adding the comment to the right of the line, but as you said it works if you add it to the line above as well. – Zev Averbach Aug 02 '22 at 12:17

Pylint warning: Possible unbalanced tuple unpacking with sequence

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