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Issue 22830: Clarify docs for functools.cmp_to_key().

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Raymond Hettinger 2014-11-09 17:20:56 -08:00
parent eb1a3cd4ea
commit 86e9b6b164
1 changed files with 5 additions and 4 deletions
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Doc/library/functools.rst
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@ -21,8 +21,8 @@ The :mod:`functools` module defines the following functions:
.. function:: cmp_to_key(func) .. function:: cmp_to_key(func)
Transform an old-style comparison function to a key function. Used with Transform an old-style comparison function to a :term:`key function`. Used
tools that accept key functions (such as :func:`sorted`, :func:`min`, with tools that accept key functions (such as :func:`sorted`, :func:`min`,
:func:`max`, :func:`heapq.nlargest`, :func:`heapq.nsmallest`, :func:`max`, :func:`heapq.nlargest`, :func:`heapq.nsmallest`,
:func:`itertools.groupby`). This function is primarily used as a transition :func:`itertools.groupby`). This function is primarily used as a transition
tool for programs being converted from Python 2 which supported the use of tool for programs being converted from Python 2 which supported the use of
@ -31,13 +31,14 @@ The :mod:`functools` module defines the following functions:
A comparison function is any callable that accept two arguments, compares them, A comparison function is any callable that accept two arguments, compares them,
and returns a negative number for less-than, zero for equality, or a positive and returns a negative number for less-than, zero for equality, or a positive
number for greater-than. A key function is a callable that accepts one number for greater-than. A key function is a callable that accepts one
argument and returns another value indicating the position in the desired argument and returns another value to be used as the sort key.
collation sequence.
Example:: Example::
sorted(iterable, key=cmp_to_key(locale.strcoll)) # locale-aware sort order sorted(iterable, key=cmp_to_key(locale.strcoll)) # locale-aware sort order
For sorting examples and a brief sorting tutorial, see :ref:`sortinghowto`.
.. versionadded:: 3.2 .. versionadded:: 3.2