mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-07-24 11:44:31 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

bpo-30969: Fix docs about the comparison in absence of __contains__ (GH-2761)

Browse source
This commit is contained in:
Antti Haapala 2019-05-30 23:19:29 +03:00 • committed by Cheryl Sabella
parent 1e36f75d63
commit 2f5b9dcc0a
1 changed files with 6 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

11
Doc/reference/expressions.rst
View file

@ -1563,14 +1563,15 @@ y`` returns ``True`` if ``y.__contains__(x)`` returns a true value, and
``False`` otherwise.
For user-defined classes which do not define :meth:`__contains__` but do define
:meth:`__iter__`, ``x in y`` is ``True`` if some value ``z`` with ``x == z`` is
produced while iterating over ``y``. If an exception is raised during the
iteration, it is as if :keyword:`in` raised that exception.
:meth:`__iter__`, ``x in y`` is ``True`` if some value ``z``, for which the
expression ``x is z or x == z`` is true, is produced while iterating over ``y``.
If an exception is raised during the iteration, it is as if :keyword:`in` raised
that exception.
Lastly, the old-style iteration protocol is tried: if a class defines
:meth:`__getitem__`, ``x in y`` is ``True`` if and only if there is a non-negative
integer index *i* such that ``x == y[i]``, and all lower integer indices do not
raise :exc:`IndexError` exception. (If any other exception is raised, it is as
integer index *i* such that ``x is y[i] or x == y[i]``, and no lower integer index
raises the :exc:`IndexError` exception. (If any other exception is raised, it is as
if :keyword:`in` raised that exception).
.. index::