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| author | Serhiy Storchaka <storchaka@gmail.com> | 2017-04-23 05:37:58 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2017-04-23 05:37:58 (GMT) |
| commit | 85157cd89a6edac347a5b6871fcf20c500c6fbbf (patch) | |
| tree | a3919bbfe70d1ce96fe9cf9dfb8fae032a9b167f | |
| parent | 997a4adea606069e01beac6269920709db3994d1 (diff) | |
| download | cpython-85157cd89a6edac347a5b6871fcf20c500c6fbbf.zip cpython-85157cd89a6edac347a5b6871fcf20c500c6fbbf.tar.gz cpython-85157cd89a6edac347a5b6871fcf20c500c6fbbf.tar.bz2 | |
bpo-15718: Document the upper bound constrain on the __len__ return value. (#1256)
| -rw-r--r-- | Doc/reference/datamodel.rst | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index 095a238..35925a0 100644 --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -2011,6 +2011,14 @@ through the container; for mappings, :meth:`__iter__` should be the same as :meth:`__bool__` method and whose :meth:`__len__` method returns zero is considered to be false in a Boolean context. + .. impl-detail:: + + In CPython, the length is required to be at most :attr:`sys.maxsize`. + If the length is larger than :attr:`!sys.maxsize` some features (such as + :func:`len`) may raise :exc:`OverflowError`. To prevent raising + :exc:`!OverflowError` by truth value testing, an object must define a + :meth:`__bool__` method. + .. method:: object.__length_hint__(self) @@ -2021,6 +2029,7 @@ through the container; for mappings, :meth:`__iter__` should be the same as .. versionadded:: 3.4 + .. note:: Slicing is done exclusively with the following three methods. A call like :: |