Pycodestyle: The preferred place to break around a binary operator is after the operator, not before it

[elopio]

Pep8 recommends to break a long line after a binary operator.
This library doesn't catch when we break before the operator.

[sigmavirus24]

You'd like a new error then for when someone does something like:

a = ('abcdefghijk'
     + 'lmnop')

Instead of

a = ('abcdefghijk' +
     'lmnop')

Correct?

[elopio]

Correct.

[glarrain]

+1

[IanLee1521]

Closed with Pull #305 . Thanks for the report!

[larsyencken]

I think this is a misreading of PEP8. The PEP allows both, but weakly recommends the opposite behaviour, suggesting Knuth's style of breaking _before the operator_ for new code.

From the PEP:

# No: operators sit far away from their operands
income = (gross_wages +
          taxable_interest +
          (dividends - qualified_dividends) -
          ira_deduction -
          student_loan_interest)

# Yes: easy to match operators with operands
income = (gross_wages
          + taxable_interest
          + (dividends - qualified_dividends)
          - ira_deduction
          - student_loan_interest)

https://www.python.org/dev/peps/pep-0008/#should-a-line-break-before-or-after-a-binary-operator

I can disable this locally for myself, but I don't think this one should be turned on by default.

[larsyencken]

Sorry for commenting on a very old issue. Looks like PEP8 has have been updated, there was more discussion about this in #498.

[IanLee1521]

@larsyencken -- No worries! That's one of the difficulties of this tool, it's trying to hit a moving target, as the actual PEP is updated from time to time.

[robvdl]

I can't get W504 passing after this fix and recent pycodestyle release.

This isn't passing:

expected_url = (CONFIG['client']['url_prefix']
                + CONFIG['client']['url_path']
                + CONFIG['client']['create_parcel'].format(service_code='runjump'))

Neither is this:

expected_url = (CONFIG['client']['url_prefix'] +
                CONFIG['client']['url_path'] +
                CONFIG['client']['create_parcel'].format(service_code='runjump'))

Is there possibly a bug in the latest pycodestyle release, or can someone tell me what I am doing wrong, in the mean time I'm having to disable W504 as this is driving me pretty crazy :)

[sigmavirus24]

@robvdl "recent pycodestyle releases" is unfortunately vague. Can you please list which versions you've tried and your configuration?

[sigmavirus24]

To be clear, W503 and W504 which control the behaviour here are both disabled by default in 2.4.0, so it's unclear how you're encountering W504: https://github.com/PyCQA/pycodestyle/blob/036461879fbfdb4ddbb689163e968d7f00ded66f/pycodestyle.py#L84

[Mausy5043]

This one bit me too today.

$ pycodestyle --ignore=E111,E221,E114,E501,C901 .
./tests/testd.py:45:24: W503 line break before binary operator
./tests/testd.py:46:24: W503 line break before binary operator
ERROR: Job failed: exit code 1

Version info:

Collecting pycodestyle
  Downloading https://files.pythonhosted.org/packages/e5/c6/blablabla/pycodestyle-2.4.0-py2.py3-none-any.whl (62kB)

Could it be that the --ignore overrides the internal defaults instead of adding to them?

[FichteFoll]

Yes, that is precisely what it does and is also mentioned in the docs.

[robvdl]

It could be possible I was getting W504 after a pycodestyle upgrade because I already had some ignores defined in setup.cfg that I was still trying to resolve after taking over a codebase.

Is it possible that once you define ignores in setup.cfg the defaults no longer apply? and therefore get replaced by my ignore list defined in setup.cfg

edit: I see I am basically asking the same question as @Mausy5043 I was observing this too.

[IanLee1521]

Yes, once you define a custom ignore, that overrides the default ignore list. If you wanted to also ignore those, you would need to manually specify them in addition to what you wanted to ignore.