https://github.com/python/cpython/commit/da63b321f63b697f75e7ab2f88f55d907f5... commit: da63b321f63b697f75e7ab2f88f55d907f56c187 branch: master author: Raymond Hettinger <rhettinger@users.noreply.github.com> committer: GitHub <noreply@github.com> date: 2019-04-28T00:22:36-07:00 summary: bpo-36715: Add usage note for dict.fromkeys() (GH-12974) files: M Doc/library/stdtypes.rst diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst index aeecdbb24a57..0a6bb149075f 100644 --- a/Doc/library/stdtypes.rst +++ b/Doc/library/stdtypes.rst @@ -4254,7 +4254,10 @@ pairs within braces, for example: ``{'jack': 4098, 'sjoerd': 4127}`` or ``{4098: Create a new dictionary with keys from *iterable* and values set to *value*. :meth:`fromkeys` is a class method that returns a new dictionary. *value* - defaults to ``None``. + defaults to ``None``. All of the values refer to just a single instance, + so it generally doesn't make sense for *value* to be a mutable object + such as an empty list. To get distinct values, use a :ref:`dict + comprehension <dict>` instead. .. method:: get(key[, default])