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| author | Raymond Hettinger <rhettinger@users.noreply.github.com> | 2021-09-21 17:26:27 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2021-09-21 17:26:27 (GMT) |
| commit | 9a0dcc5b2e04d9c51350107734f12a1cbc0284a7 (patch) | |
| tree | 249f4bdfdc56559c706bb2bbf7445e0931f1a873 | |
| parent | a356272362c15f2561872f3206baf5e9a0543997 (diff) | |
| download | cpython-9a0dcc5b2e04d9c51350107734f12a1cbc0284a7.zip cpython-9a0dcc5b2e04d9c51350107734f12a1cbc0284a7.tar.gz cpython-9a0dcc5b2e04d9c51350107734f12a1cbc0284a7.tar.bz2 | |
bpo-45246: Document that sorted() only uses "<" comparisons (GH-28494)
| -rw-r--r-- | Doc/library/functions.rst | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst index a8fc702..19d67e9 100644 --- a/Doc/library/functions.rst +++ b/Doc/library/functions.rst @@ -1592,6 +1592,15 @@ are always available. They are listed here in alphabetical order. compare equal --- this is helpful for sorting in multiple passes (for example, sort by department, then by salary grade). + The sort algorithm uses only ``<`` comparisons between items. While + defining an :meth:`~object.__lt__` method will suffice for sorting, + :PEP:`8` recommends that all six :ref:`rich comparisons + <comparisons>` be implemented. This will help avoid bugs when using + the same data with other ordering tools such as :func:`max` that rely + on a different underlying method. Implementing all six comparisons + also helps avoid confusion for mixed type comparisons which can call + reflected the :meth:`~object.__gt__` method. + For sorting examples and a brief sorting tutorial, see :ref:`sortinghowto`. .. decorator:: staticmethod |