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| author | Jeroen Demeyer <J.Demeyer@UGent.be> | 2019-09-10 16:01:13 +0200 |
|---|---|---|
| committer | Steve Dower <steve.dower@python.org> | 2019-09-10 15:01:13 +0100 |
| commit | 009ef2955d91e04f62a7159a1c7ddaddbfedc3b6 (patch) | |
| tree | a52b3f51141110fa2ca7a8f1ec2f8ee745f54d25 /Doc/reference | |
| parent | 17499d82702432955d8e442a1871ff276ca64bc5 (diff) | |
| download | cpython-git-009ef2955d91e04f62a7159a1c7ddaddbfedc3b6.tar.gz | |
bpo-37913: document that __length_hint__ can return NotImplemented (GH-15383)
Diffstat (limited to 'Doc/reference')
| -rw-r--r-- | Doc/reference/datamodel.rst | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index 8813f57587..6b9325da2f 100644 --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -2155,8 +2155,10 @@ through the container; for mappings, :meth:`__iter__` should be the same as Called to implement :func:`operator.length_hint`. Should return an estimated length for the object (which may be greater or less than the actual length). - The length must be an integer ``>=`` 0. This method is purely an - optimization and is never required for correctness. + The length must be an integer ``>=`` 0. The return value may also be + *NotImplemented*, which is treated the same as if the ``__length_hint__`` + method didn't exist at all. This method is purely an optimization and is + never required for correctness. .. versionadded:: 3.4 |