What's New in Pylint 2.10#

Release

2.10

Date

2021-08-20

Summary -- Release highlights#

In 2.10, we added several new default check, like unspecified-encoding, forgotten-debug-statement or use-dict-literal. There's also a few opinionated optional one. You can now forbid while loop or profess your exclusive love of ternary expressions publicly. We promise you hours of arguing fun with your whole team if you add those to your configuration.

We've also fixed some long standing bugs, false positives, or missing options like ignore-signature that will now work on inner function's signatures.

A new option to disable the next line, disable-next, has been added. It's also possible to export colored diagrams, and plantuml diagram using pyreverse. PYLINT_HOME is now XDG_CACHE_HOME if not set.

The performance of the similarity checker has been improved, as well as several small performance fixes.

We're going to continue working on improving performance during 2.11. We're also going to finalize a new possible-forgotten-f-prefix check that had too much false positives at release time. Check the possible-forgotten-f-prefix issue if you want to provide knowledge or use case :)

New checkers#

  • Added unspecified-encoding: Emitted when open() is called without specifying an encoding

    Closes #3826

  • Added use-list-literal: Emitted when list() is called with no arguments instead of using []

    Closes #4365

  • Added use-dict-literal: Emitted when dict() is called with no arguments instead of using {}

    Closes #4365

  • Added forgotten-debug-statement: Emitted when breakpoint, pdb.set_trace or sys.breakpointhook calls are found

    Closes #3692

  • Added use-sequence-for-iteration: Emitted when iterating over an in-place defined set.

  • Added format-string-without-interpolation checker: Emitted when formatting is applied to a string without any variables to be replaced

    Closes #4042

  • Added redundant-u-string-prefix checker: Emitted when the u prefix is added to a string

    Closes #4102

Extensions#

  • CodeStyleChecker

    • Limit consider-using-tuple to be emitted only for in-place defined lists.

    • Emit consider-using-tuple even if list contains a starred expression.

  • Added optional extension consider-ternary-expression: Emitted whenever a variable is assigned in both branches of an if/else block.

    Closes # 4366

  • Added optional extension while-used: Emitted whenever a while loop is used.

    Closes # 4367

Other Changes#

  • pyreverse now permit to produce colored generated diagram by using the colorized option.

  • Pyreverse - add output in PlantUML format

  • consider-using-with is no longer triggered if a context manager is returned from a function.

  • pylint does not crash with a traceback anymore when a file is problematic. It creates a template text file for opening an issue on the bug tracker instead. The linting can go on for other non problematic files instead of being impossible.

  • Pyreverse - Show class has-a relationships inferred from type-hints

  • Performance of the Similarity checker has been improved.

  • Added time.clock to deprecated functions/methods for python 3.3

  • Added ignored-parents option to the design checker to ignore specific classes from the too-many-ancestors check (R0901).

  • Don't emit no-member error if guarded behind if statement.

    Ref #1162 Closes #1990 Closes #4168

  • Fix false positives for superfluous-parens with walrus operator, ternary operator and inside list comprehension.

    Closes #2818 Closes #3249 Closes #3608 Closes #4346

  • Refactor of --list-msgs & --list-msgs-enabled: both options now show whether messages are emittable with the current interpreter.

    Closes #4778

  • Fix false negative for used-before-assignment when the variable is assigned in an exception handler, but used outside of the handler.

    Closes #626

  • Added disable-next option: allows using # pylint: disable-next=msgid to disable a message for the following line

    Closes #1682

  • Fixed cell-var-from-loop checker: handle cell variables in comprehensions within functions, and function default argument expressions. Also handle basic variable shadowing.

    Closes #2846 Closes #3107

  • Fixed bug with cell-var-from-loop checker: it no longer has false negatives when both unused-variable and used-before-assignment are disabled.

  • Class methods' signatures are now ignored the same way as functions' with similarities "ignore-signatures" option enabled

    Closes #4653