What's New In Pylint 1.6
************************

Release:
   1.6.0

Date:
   2016-07-07


Summary -- Release highlights
=============================

Nothing major.


New checkers
============

* We added a new recommendation check, "consider-iterating-
  dictionary", which is emitted when a dictionary is iterated by using
  ".keys()".

  For instance, the following code would trigger this warning, since
  the dictionary's keys can be iterated without calling the method
  explicitly.

     for key in dictionary.keys():
         ...

     # Can be refactored to:
     for key in dictionary:
         ...

* "trailing-newlines" check was added, which is emitted when a file
  has trailing newlines.

* "invalid-length-returned" check was added, which is emitted when the
  "__len__" special method returns something else than a non-negative
  number. For instance, this example is triggering it:

     class Container(object):
         def __len__(self):
             return self._items # Oups, forgot to call len() over it.

* Add a new check to the *check_docs* extension for looking for
  duplicate constructor parameters in a class constructor docstring or
  in a class docstring.

  The check "multiple-constructor-doc" is emitted when the parameter
  is documented in both places.

* We added a new extension plugin, "pylint.extensions.mccabe", which
  can be used for warning about the complexity in the code.

  You can enable it as in:

     $ pylint module_or_project --load-plugins=pylint.extensions.mccabe

  See more at Design checker


New features
============

* "generated-members" now supports qualified names through regular
  expressions.

  For instance, for ignoring all the errors generated by
  "numpy.core"'s attributes, we can now use:

     $ pylint a.py --generated-members=numpy.*

* Add the ability to ignore files based on regex matching, with the
  new "--ignore-patterns" option.

  Rather than clobber the existing "ignore" option, we decided to have
  a separate option for it. For instance, for ignoring all the test
  files, we can now use:

     $ pylint myproject --ignore-patterns=test.*?py

* We added a new option, "redefining-builtins-modules", which is used
  for defining the modules which can redefine builtins. *pylint* will
  emit an error when a builtin is redefined, such as defining a
  variable called "next". But in some cases, the builtins can be
  redefined in the case they are imported from other places, different
  than the "builtins" module, such is the case for "six.moves", which
  contains more forward-looking functions:

     $ cat a.py
     # Oups, now pylint emits a redefined-builtin message.
     from six.moves import open
     $ pylint a.py --redefining-builtins-modules=six.moves

  Default values: "six.moves,future.builtins"


Bug fixes
=========

* Fixed a bug where the top name of a qualified import was detected as
  an unused variable.

* We don't warn about "invalid-sequence-index" if the indexed object
  has unknown base classes, that Pylint cannot deduce.


Other Changes
=============

* The "bad-builtin" check was moved into an extension.

  The check was complaining about used builtin functions which were
  supposed to not be used. For instance, "map" and "filter" were
  falling into this category, since better alternatives can be used,
  such as list comprehensions. But the check was annoying, since using
  "map" or "filter" can have its use cases and as such, we decided to
  move it to an extension check instead. It can now be enabled through
  "--load-plugins=pylint.extensions.bad_builtin".

* We use the "configparser" backport internally, for Python 2.

  This allows having comments inside list values, in the
  configuration, such as:

     disable=no-member,
             # Don't like this check
             bad-indentation

* We now use the isort package internally.

  This improves the "`wrong-import-order" check, so now we should have
  less false positives regarding the import order.

* We do not emit "import-error" or "no-name-in-module" for fallback
  import blocks by default.

  A fallback import block can be considered a TryExcept block, which
  contains imports in both branches, such as:

     try:
         import urllib.request as request
     except ImportError:
         import urllib2 as request

  In the case where **pylint** can not find one import from the
  "except" branch, then it will emit an "import-error", but this gets
  cumbersome when trying to write compatible code for both Python
  versions. As such, we don't check these blocks by default, but the
  analysis can be enforced by using the new "--analyse-fallback-block"
  flag.

* "reimported" is emitted when the same name is imported from
  different module, as in:

     from collections import deque, OrderedDict, deque


Deprecated features
===================

* The HTML support was deprecated and will be eventually removed in
  Pylint 1.7.0.

  This feature was lately a second class citizen in Pylint, being
  often neglected and having a couple of bugs. Since we now have the
  JSON reporter, this can be used as a basis for more prettier HTML
  outputs than what Pylint can currently offer.

* The "--files-output" option was deprecated and will be eventually
  removed in Pylint 1.7.0.

* The "--optimize-ast" option was deprecated and will be eventually
  removed in Pylint 1.7.0.

  The option was initially added for handling pathological cases, such
  as joining too many strings using the addition operator, which was
  leading pylint to have a recursion error when trying to figure out
  what the string was. Unfortunately, we decided to ignore the issue,
  since the pathological case would have happen when the code was
  parsed by Python as well, without actually reaching the runtime step
  and as such, we will remove the option in the future.

* The "check_docs" extension is now deprecated. The extension is still
  available under the "docparams" name, so this should work:

     $ pylint module_or_package --load-extensions=pylint.extensions.docparams

  The old name is still kept for backward compatibility, but it will
  be eventually removed.


Removed features
================

* None yet
