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Diffstat (limited to 'Doc/reference/datamodel.rst')
| -rw-r--r-- | Doc/reference/datamodel.rst | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index d1702cc..8813f57 100644 --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -1618,21 +1618,32 @@ refers to the attribute whose name is the key of the property in the owner class' :attr:`~object.__dict__`. -.. method:: object.__get__(self, instance, owner) +.. method:: object.__get__(self, instance, owner=None) - Called to get the attribute of the owner class (class attribute access) or of an - instance of that class (instance attribute access). *owner* is always the owner - class, while *instance* is the instance that the attribute was accessed through, - or ``None`` when the attribute is accessed through the *owner*. This method - should return the (computed) attribute value or raise an :exc:`AttributeError` - exception. + Called to get the attribute of the owner class (class attribute access) or + of an instance of that class (instance attribute access). The optional + *owner* argument is the owner class, while *instance* is the instance that + the attribute was accessed through, or ``None`` when the attribute is + accessed through the *owner*. + This method should return the computed attribute value or raise an + :exc:`AttributeError` exception. + + :PEP:`252` specifies that :meth:`__get__` is callable with one or two + arguments. Python's own built-in descriptors support this specification; + however, it is likely that some third-party tools have descriptors + that require both arguments. Python's own :meth:`__getattribute__` + implementation always passes in both arguments whether they are required + or not. .. method:: object.__set__(self, instance, value) Called to set the attribute on an instance *instance* of the owner class to a new value, *value*. + Note, adding :meth:`__set__` or :meth:`__delete__` changes the kind of + descriptor to a "data descriptor". See :ref:`descriptor-invocation` for + more details. .. method:: object.__delete__(self, instance) |