E731: assignment of lambda is not detected if parenthesized
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Description
$ cat foo.py
foo = lambda x: x
bar = (lambda x: x)
$ pycodestyle foo.py
foo.py:1:1: E731 do not assign a lambda expression, use a def
The second case is not detected. (A realistic case is when the parentheses are used for line continuation, e.g.
bar = (
lambda ...: ...
)
)
Note that I agree that lambdas inside e.g. ternaries (#845) should not trigger a warning; this report is explicitly only for the case where a lambda is the sole thing being parenthesized.
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Research direction
Run the reported pycodestyle foo.py example and trace the E731 check that flags direct lambda assignments. Add coverage for a lambda that is the sole expression inside parentheses, including the line-continuation form, while preserving the behavior for lambdas inside ternaries; done means both cases are distinguished correctly.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 52/100