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author | Raymond Hettinger <python@rcn.com> | 2014-11-10 01:10:17 (GMT) |
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committer | Raymond Hettinger <python@rcn.com> | 2014-11-10 01:10:17 (GMT) |
commit | ccae479e2de19a042a75a1c1e1cdca7453de86f6 (patch) | |
tree | 65c3dc998a38d844302266df96d22501dcbf445e /Doc | |
parent | fb136d19ff57d42cad9a7177ba8fdad3ef1577c6 (diff) | |
download | cpython-ccae479e2de19a042a75a1c1e1cdca7453de86f6.zip cpython-ccae479e2de19a042a75a1c1e1cdca7453de86f6.tar.gz cpython-ccae479e2de19a042a75a1c1e1cdca7453de86f6.tar.bz2 |
Issue 22830: Clarify docs for functools.cmp_to_key().
Diffstat (limited to 'Doc')
-rw-r--r-- | Doc/library/functools.rst | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/Doc/library/functools.rst b/Doc/library/functools.rst index 9336f79..086b0b5 100644 --- a/Doc/library/functools.rst +++ b/Doc/library/functools.rst @@ -22,8 +22,8 @@ The :mod:`functools` module defines the following functions: .. function:: cmp_to_key(func) - Transform an old-style comparison function to a key function. Used with - tools that accept key functions (such as :func:`sorted`, :func:`min`, + Transform an old-style comparison function to a :term:`key function`. Used + with tools that accept key functions (such as :func:`sorted`, :func:`min`, :func:`max`, :func:`heapq.nlargest`, :func:`heapq.nsmallest`, :func:`itertools.groupby`). This function is primarily used as a transition tool for programs being converted to Python 3 where comparison functions are @@ -32,13 +32,16 @@ The :mod:`functools` module defines the following functions: 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 number for greater-than. A key function is a callable that accepts one - argument and returns another value that indicates the position in the desired - collation sequence. + argument and returns another value to be used as the sort key. Example:: sorted(iterable, key=cmp_to_key(locale.strcoll)) # locale-aware sort order + For sorting examples and a brief sorting tutorial, see `Sorting HowTo + <https://wiki.python.org/moin/HowTo/Sorting/>`_\. + + .. versionadded:: 2.7 .. function:: total_ordering(cls) |