What's New in Pylint 4.0¶

:Release:4.0 :Date: TBA

Summary -- Release highlights¶

Release date: TBA

invalid-name now distinguishes module-level constants that are assigned only once from those that are reassigned and now applies --variable-rgx to the latter. Values other than literals (lists, sets, objects) can pass against either the constant or variable regexes (e.g. "LOGGER" or "logger" but not "LoGgEr").

Remember that --good-names or --good-names-rgxs can be provided to explicitly allow good names.

Closes #3585 (#3585)
Commented out code blocks such as # bar() # TODO: remove dead code will no longer emit fixme.

Refs #9255 (#9255)
pyreverse Run was changed to no longer call sys.exit() in its __init__. You should now call Run(args).run() which will return the exit code instead. Having a class that always raised a SystemExit exception was considered a bug.

Normal usage of pyreverse through the CLI will not be affected by this change.

Refs #9689 (#9689)
The async.py checker module has been renamed to async_checker.py since async is a Python keyword and cannot be imported directly. This allows for better testing and extensibility of the async checker functionality.

Refs #10071 (#10071)

The fixme check can now search through docstrings as well as comments, by using check-fixme-in-docstring = true in the [tool.pylint.miscellaneous] section.

Closes #9255 (#9255)
Enhanced support for @property decorator in pyreverse to correctly display return types of annotated properties when generating class diagrams.

Closes #10057 (#10057)
Add --max-depth option to pyreverse to control diagram complexity. A depth of 0 shows only top-level packages, 1 shows one level of subpackages, etc. This helps manage visualization of large codebases by limiting the depth of displayed packages and classes.

Refs #10077 (#10077)
pyreverse: add support for colorized output when using output format mmd (MermaidJS) and html.

Closes #10242 (#10242)

Fix a false positive for used-before-assignment when an inner function's return type annotation is a class defined at module scope.

Closes #9391 (#9391)
Fix a false positive for used-before-assignment when a variable defined under an if and via a named expression (walrus operator) is used later when guarded under the same if test.

Closes #10061 (#10061)
Fix false positives for use-implicit-booleaness-not-comparison, use-implicit-booleaness-not-comparison-to-string and use-implicit-booleaness-not-comparison-to-zero when chained comparisons are checked.

Closes #10065 (#10065)
Fix a false positive for invalid-getnewargs-ex-returned when the tuple or dict has been assigned to a name.

Closes #10208 (#10208)
Remove getopt and optparse from the list of deprecated modules.

Closes #10211 (#10211)

Fix false negative for used-before-assignment when a TYPE_CHECKING import is used as a type annotation prior to erroneous usage.

Refs #8893 (#8893)
Check module-level constants with type annotations for invalid-name. Remember to adjust const-naming-style or const-rgx to your liking.

Closes #9770 (#9770)
Fix false negative for used-before-assignment when a function is defined inside a TYPE_CHECKING guard block and used later.

Closes #10028 (#10028)

Fixes "skipped files" count calculation; the previous method was displaying an arbitrary number.

Closes #10073 (#10073)
Fixed conditional import x.y causing false positive possibly-used-before-assignment.

Closes #10081 (#10081)
Fixes a crash that occurred when pylint was run in a container on a host with cgroupsv2 and restrictions on CPU usage.

Closes #10103 (#10103)
Fix a crash when something besides a class is found in an except handler.

Closes #10106 (#10106)
Fixed raising invalid-name when using camelCase for private methods with two leading underscores.

Closes #10189 (#10189)
Relaxed the requirements for isort so pylint can benefit from isort 6.

Closes #10203 (#10203)
Fixed unidiomatic-typecheck only checking left-hand side.

Closes #10217 (#10217)