Frequently Asked Questions¶
How do I install Pylint?¶
For command line use, pylint is installed with:
pip install pylint
Or if you want to also check spelling with enchant
(you might need to
install the enchant C library):
pip install pylint[spelling]
It can also be integrated in most editors or IDEs. More information can be found in the documentation.
How do I contribute to Pylint?¶
We welcome all forms of contributions such as updates for documentation, new code, checking issues for duplicates or telling us that we can close them, confirming that issues still exist, creating issues because you found a bug or want a feature, etc. Everything is much appreciated!
Please follow the code of conduct and check the Contributor Guides if you want to make a code contribution.
Does Pylint follow a versioning scheme?¶
How do I find the name corresponding to a specific command line option?¶
What is the format of the configuration file?¶
The configuration file can be an ini
or toml
file. See the exhaustive list of possible options.
How to disable a particular message?¶
Read Messages control for details and examples.
Pylint gave my code a negative rating out of ten. That can't be right!¶
Prior to Pylint 2.13.0, the score formula used by default had no lower bound. The new default score formula is
max(0, 0 if fatal else 10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10))
If your project contains a configuration file created by an earlier version of
Pylint, you can set evaluation
to the above expression to get the new
behavior. Likewise, since negative values are still technically supported,
evaluation
can be set to a version of the above expression that does not
enforce a floor of zero.
How do I avoid getting unused argument warnings for API I do not control?¶
Prefix (ui) the callback's name by cb_ (callback), as in cb_onclick(...). By doing so arguments usage won't be checked. Another solution is to use one of the names defined in the "dummy-variables" configuration variable for unused argument ("_" and "dummy" by default).
Why are there a bunch of messages disabled by default?¶
Either because they are prone to false positives or that they are opinionated enough to not be included as default messages.
You can see the plugin you need to explicitly load in the technical reference.
I want to use pylint on each keystroke in my IDE, how can I do that ?¶
Don't do it: pylint's full suite of checks is not fast enough for that and never
will be. pylint is best suited for linting on save for small projects, or for a continuous
integration job or a git pre-push
hook for big projects. The larger your repository
is, the slower pylint will be.
If you want to make pylint faster for this type of use case, you can use the --errors-only
option, which will remove all the refactor, convention, and warning checks. You can also disable
checks with inherently high complexity that need to analyse the full code base like
duplicate-code
or cyclic-import
(this list is not exhaustive).
Why do I have non-deterministic results when I try to parallelize pylint ?¶
pylint should analyse all your code at once in order to best infer the
actual values that result from calls. If only some of the files are given, pylint might
miss a particular value's type and produce inferior inference for the subset. Parallelization
of pylint is not easy; we also discourage the use of the -j
option if this matters to you.
Which messages should I disable to avoid duplicates if I use other popular linters ?¶
pycodestyle: bad-indentation, bare-except, line-too-long, missing-final-newline, multiple-statements, singleton-comparison, trailing-newlines, trailing-whitespace, unnecessary-negation, unnecessary-semicolon, wrong-import-position
pyflakes: undefined-variable, unused-import, unused-variable
mccabe: too-many-branches
pydocstyle: missing-module-docstring, missing-class-docstring, missing-function-docstring
pep8-naming: invalid-name, bad-classmethod-argument, bad-mcs-classmethod-argument, no-self-argument
isort and flake8-import-order: wrong-import-order
How do I avoid "access to undefined member" messages in my mixin classes?¶
You should add the no-member
message to your ignored-checks-for-mixins
option
and name your mixin class with a name which ends with "Mixin" or "mixin" (default)
or change the default value by changing the mixin-class-rgx
option.
Where is the persistent data stored to compare between successive runs?¶
Analysis data are stored as a pickle file in a directory which is localized using the following rules:
value of the PYLINTHOME environment variable if set
- "pylint" subdirectory of the user's XDG_CACHE_HOME if the environment variable is set, otherwise
Linux: "~/.cache/pylint"
macOS: "~/Library/Caches/pylint"
Windows: "C:Users<username>AppDataLocalpylint"
".pylint.d" directory in the current directory