What's New in Pylint 2.11#

Release

2.11

Date

2021-09-16

Summary -- Release highlights#

In 2.11, we added a new default checker to advise using f-string as it's the most efficient way of formatting strings right now. You can use pyupgrade or flynt to migrate your old % and format() automatically.

We added a new extension SetMembershipChecker that will advise the use of set for membership test, as it's more performant than lists or tuples. The CodeStyleChecker also got some love, check it out if you're not already using it.

We fixed some long standing bugs, false positives, or false negatives and we added small quality of life options like min-similarity-lines that disable the duplication check when set to 0.

Under the hood the code for both pylint and astroid is progressively more typed, which could be helpful to you if you're using them as libraries. In order for this new typing to make more sense and stay simple, we deprecated some functions or type that will be removed in the next major version. This is an ongoing effort.

The future possible-forgotten-f-prefix check still had too much false positives, and is delayed again. Check the possible-forgotten-f-prefix issue if you want to provide knowledge or use case :)

New checkers#

  • Added consider-using-f-string: Emitted when .format() or '%' is being used to format a string.

    Closes #3592

Removed checkers#

  • The python3 porting mode checker and it's py3k option were removed. You can still find it in older pylint versions.

Extensions#

  • Added new extension SetMembershipChecker with use-set-for-membership check: Emitted when using an in-place defined list or tuple to do a membership test. sets are better optimized for that.

    Closes #4776

  • CodeStyleChecker

    • Added consider-using-assignment-expr: Emitted when an assignment is directly followed by an if statement and both can be combined by using an assignment expression :=. Requires Python 3.8

      Closes #4862

Other Changes#

  • Added py-version config key (if [MAIN] section). Used for version dependent checks. Will default to whatever Python version pylint is executed with.

  • The invalid-name message is now more detailed when using multiple naming style regexes.

  • Fix false positive for consider-using-with if a context manager is assigned to a variable in different paths of control flow (e. g. if-else clause).

    Closes #4751

  • Fix false positive for function-redefined for simple type annotations

    Closes #4936

  • Fix false positive for protected-access if a protected member is used in type hints of function definitions

  • Fix false positive dict-iter-missing-items for dictionaries only using tuples as keys

    Closes #3282

  • The unspecified-encoding checker now also checks calls to pathlib.Path().read_text() and pathlib.Path().write_text()

    Closes #4945

  • Fix false positive superfluous-parens for tuples created with inner tuples

    Closes #4907

  • Fix false positive unused-private-member for accessing attributes in a class using cls

    Closes #4849

  • Extended consider-using-in check to work for attribute access.

  • Setting min-similarity-lines to 0 now makes the similarty checker stop checking for duplicate code

    Closes #4901

  • Fix a bug where pylint complained if the cache's parent directory does not exist

    Closes #4900

  • The global-variable-not-assigned checker now catches global variables that are never reassigned in a local scope and catches (reassigned) functions

    Closes #1375 Closes #330

  • The consider-iterating-dictionary checker now also considers membership checks

    Closes #4069