************************** What's New in Pylint 2.9 ************************** :Release: 2.9 :Date: 2021-06-29 Summary -- Release highlights ============================= Pylint is now compatible with python 3.10. A lot of new checks have been added, some non-opinionated performance warnings like ``use-maxsplit-arg``, some consensual style warnings like ``unnecessary-dict-index-lookup`` or new deprecation checks. We're aiming to reduce pylint noise for first time users and making some new checks optional is a step in that direction. In order to do that we created an optional code style checker that can be loaded using ``pylint.extensions.code_style`` with the ``load-plugins`` options. More than ever, if as a veteran you want the most checks you can possibly get, `you should check the list of pylint extensions. `_. New checkers ============ * ``deprecated-decorator``: Emitted when deprecated decorator is used. * ``consider-using-dict-items``: Emitted when iterating over dictionary keys and then indexing the same dictionary with the key within loop body. * ``use-maxsplit-arg``: Emitted either when accessing only the first or last element of ``str.split()``. * An ``ignore_signatures`` option has been added to the similarity checker. It will permits to reduce false positives when multiple functions have the same parameters. * ``unnecessary-dict-index-lookup``: Emitted when iterating over dictionary items (key-value pairs) and accessing the value by index lookup. * ``consider-using-from-import``: Emitted when a submodule/member of a package is imported and aliased with the same name. * New checker ``unused-private-member``: Emitted when a private member (i.e., starts with ``__``) of a class is defined but not used. * New checker ``invalid-class-object``: Emitted when a non-class is assigned to a ``__class__`` attribute. * ``invalid-all-format``: Emitted when ``__all__`` has an invalid format, i.e. isn't a ``tuple`` or ``list``. * New checker ``await-outside-async``: Emitted when await is used outside an async function. * Add new extension ``CodeStyleChecker``. It includes checkers that can improve code consistency. As such they don't necessarily provide a performance benefit and are often times opinionated. * ``consider-using-tuple``: Emitted when an in-place defined list or set can be replaced by a tuple. * ``consider-using-namedtuple-or-dataclass``: Emitted when dictionary values can be replaced by namedtuples or dataclass instances. Other Changes ============= * Fix false-positive ``consider-using-with`` (R1732) if a ternary conditional is used together with ``with`` * Fix false-positive ``consider-using-with`` (R1732) if ``contextlib.ExitStack`` takes care of calling the ``__exit__`` method * Add type annotations to pyreverse dot files * Pylint's tags are now the standard form ``vX.Y.Z`` and not ``pylint-X.Y.Z`` anymore. * Fix false-positive ``too-many-ancestors`` when inheriting from builtin classes, especially from the ``collections.abc`` module * The output messages for ``arguments-differ`` error message have been customized based on the different error cases. * New option ``--fail-on=`` to return non-zero exit codes regardless of ``fail-under`` value. * A new error called ``arguments-renamed`` has been created, which identifies any changes at the parameter names of overridden functions. It aims to separate the functionality of ``arguments-differ``. * Fix incompatibility with Python 3.6.0 caused by ``typing.Counter`` and ``typing.NoReturn`` usage * Allow comma-separated list in ``output-format`` and separate output files for each specified format. Each output file can be defined after a semicolon for example : ``--output-format=json:myfile.json,colorized`` * The ``using-constant-test`` checker now detects constant tests consisting of list literals like ``[]`` and ``[1, 2, 3]``. * ``ignore-paths`` configuration directive has been added. Defined regex patterns are matched against file path. * Added handling of floating point values when parsing configuration from pyproject.toml * Fix false positive ``useless-type-doc`` on ignored argument using ``pylint.extensions.docparams`` when a function was typed using pep484 but not inside the docstring. * Fix missing support for detecting deprecated aliases to existing functions/methods. functions/methods. * Added various deprecated functions/methods for python 3.10, 3.7, 3.6 and 3.3 * No longer emit ``consider-using-with`` for ``ThreadPoolExecutor`` and ``ProcessPoolExecutor`` as they have legitimate use cases without a ``with`` block. * Fix crash if a callable returning a context manager was assigned to a list or dict item