wemake-services/flake8-broken-line

🚨 Flake8 plugin to forbid backslashes (\) for line breaks

flake8-broken-line

Do not break the line! 🚨

Installation

pip install flake8-broken-line

It is also a valuable part of wemake-python-styleguide.

Code example

Things we check with this plugin:

# String line breaks, use `()` or `"""` instead:

some_string = 'first line\
second line'

# Use a single line, `()`, or new variables instead:

if 1 == 1 and \
    2 == 2:
    print('Do not do that!')

# Do not use for method chaining:
some_object \
  .call_method(param1, param2) \
  .call_other(keyword=value) \
  .finalize()

# Instead use:
some_objects.call_method(
    param1, param2,
).call_other(
    keyword=value
).finalize()

Error codes

Error code	Description
N400	Found backslash that is used for line breaking

License

MIT.

flake8-broken-line's Issues

False-positive for backslashes in multiline strings

Minimal code to reproduce:

"""
\
"""

[N400] How to short imports?

If I have a long import then how should I short it?
I have this:

from app.baz.bar.foo.first_word.second_word.handler import post as first_word_second_word_scoring

And it is longer than 100 symbols in one line. Isort does the following for me:

from app.baz.bar.foo.first_word.second_word.handler import \
    post as first_word_second_word_scoring

And I got: N400: Found backslash that is used for line breaking

PEP8 backslash exception for `with` statements is not honored

Given this example, explicitly allowed by PEP8 (lit. Backslashes may still be appropriate at times. For example, long, multiple with-statements cannot use implicit continuation, so backslashes are acceptable):

async def fnc():
    async with asdf() as a, \
               bsdf():
        return 1

with asdf() as a, \
     bsdf():
    return 1


with \
  asdf() as a, \
  bsdf():
    return 1

This plugin gives many non-PEP8-compliant false positives:

test_continuation.py:2:1: N400: Found backslash that is used for line breaking
    async with asdf() as a, \
               bsdf():
^
test_continuation.py:6:1: N400: Found backslash that is used for line breaking
with asdf() as a, \
     bsdf():
^
test_continuation.py:11:1: N400: Found backslash that is used for line breaking
with \
  asdf() as a, \
  bsdf():
^
test_continuation.py:12:3: N400: Found backslash that is used for line breaking
with \
  asdf() as a, \
  bsdf():
  ^

How to chain methods without arguments?

Thank you for your great strict linting job! I have an IRL question, and maybe it's a good idea to add more examples to README.

For example I have long chain of methods without arguments:

some_object \
  .call_method() \
  .call_other() \
  .finalize()

So it should be:

some_objects.call_method(

).call_other(

).finalize()

or

some_objects.call_method(
).call_other(
).finalize()

?

Support for flake8 4.x

Hi,

Trying to update flake8 to 4.x is not possible because this extension forces it to be <4.0. Probably there isn't any broken changes, but the dependency needs to be loosen

Compat with flake8 >= 6

"SolverProblemError

Because flake8-broken-line (0.6.0) depends on flake8 (>=3.5,<6) and no versions of flake8-broken-line match >0.6.0,<0.7.0, flake8-broken-line (>=0.6.0,<0.7.0) requires flake8 (>=3.5,<6). So, because project depends on both flake8 (^6.0.0) and flake8-broken-line (^0.6.0), version solving failed."

Please release new version

A recent change made this plugin work with flake8 version 5, but this is still unreleased and actively blocking from migrating to the new flake8 version.

Dependabot can't resolve your Python dependency files

Dependabot can't resolve your Python dependency files.

As a result, Dependabot couldn't update your dependencies.

The error Dependabot encountered was:

Creating virtualenv flake8-broken-line-M5gsrVWi-py3.8 in /home/dependabot/.cache/pypoetry/virtualenvs
Updating dependencies
Resolving dependencies...

[PackageNotFound]
Package pytest-isort (0.3.1) not found.

If you think the above is an error on Dependabot's side please don't hesitate to get in touch - we'll do whatever we can to fix it.

View the update logs.

'''\ Is detected as line break in triple quoted strings

flake8 --version
3.8.2 (flake8-broken-line: 0.2.0, flake8-bugbear: 20.1.4, flake8-colors:
0.1.0, flake8-comprehensions: 3.2.2, flake8-eradicate: 0.3.0, flake8_commas:
2.0.0, flake8_isort: 3.0.0, mccabe: 0.6.1, pycodestyle: 2.6.0, pyflakes:
2.2.0) CPython 3.6.3 on Linux

code to repro

'''\
'''

The \ there is used to elminate the newline from the literal string block as noted 1/2 page down or so here (https://docs.python.org/3.6/tutorial/introduction.html#strings)

String literals can span multiple lines. One way is using triple-quotes: """...""" or '''...'''. End of lines are automatically included in the string, but it’s possible to prevent this by adding a \ at the end of the line. The following example:

Backslash at end of comment incorrectly detected

A backslash at the end of a comment is detected as a line-breaking slash.

# A remote path can be entered.  e.g.:  \\server\

N400: Found backslash that is used for line braking

Backslashes in rf strings not honored as in r strings.

Example

This works as expected:

an_r_string = r'''
    Hello \
    World
'''

But this raises an error:

planet = 'Earth'
an_r_string = fr'''
    Hello \
    {planet}
'''

Fix the CI and update deps

Currently, there are errors in our CI: https://travis-ci.com/github/sobolevn/flake8-broken-line/jobs/334338507

It needs to be fixed. Probably it would be safe to say that poetry update will do the thing.
And it is also required to update lots of deps from @dependabot-bot updates that are not mergable at the moment.
List: https://github.com/sobolevn/flake8-broken-line/pulls

Add python3.9 support

Dependabot couldn't authenticate with https://pypi.python.org/simple/

Dependabot couldn't authenticate with https://pypi.python.org/simple/.

You can provide authentication details in your Dependabot dashboard by clicking into the account menu (in the top right) and selecting 'Config variables'.

View the update logs.

Support python3.8

Related wemake-services/wemake-python-styleguide#1138

Dependabot can't resolve your Python dependency files

Dependabot can't resolve your Python dependency files.

As a result, Dependabot couldn't update your dependencies.

The error Dependabot encountered was:

Creating virtualenv flake8-broken-line-TAFSsRl8-py3.8 in /home/dependabot/.cache/pypoetry/virtualenvs
Updating dependencies
Resolving dependencies...

[PackageNotFound]
Package pytest-isort (0.3.1) not found.

If you think the above is an error on Dependabot's side please don't hesitate to get in touch - we'll do whatever we can to fix it.

View the update logs.

Typo: "Found backslash that is used for line breaking"

Not "braking". Thanks to https://www.reddit.com/r/Python/comments/aldo62/flake8brokenline_flake8_plugin_to_forbid_in_your/effvbh2/

What does "do not reimplement chaining" mean?

The first two examples are good because they provide reasonable alternatives to using the line break. But the third, I'm not sure what it means. How is the programming "implementing" chaining? Can we just suggest a Pythonic alternative instead?

Dependabot can't resolve your Python dependency files

Dependabot can't resolve your Python dependency files.

As a result, Dependabot couldn't update your dependencies.

The error Dependabot encountered was:

Creating virtualenv flake8-broken-line-KHe-WgIB-py3.8 in /home/dependabot/.cache/pypoetry/virtualenvs
Updating dependencies
Resolving dependencies...

[PackageNotFound]
Package pytest-isort (0.3.1) not found.

If you think the above is an error on Dependabot's side please don't hesitate to get in touch - we'll do whatever we can to fix it.

View the update logs.

Broken line in triple quotes

If i have:

text = """
...
very long line 1 - very long line 2
...
"""

So i have E501 (line to long). This is not so beautiful, so i change:

text = """
...
very long line 1 - \
very long line 2
...
"""

And now i have N400 (Found backslash that is used for line braking)

What should i do on this?