New submission from Jan Kaliszewski:
1. One misleading detail in the descriptor protocol documentation for super
bindings is that the following fragment of the
http://docs.python.org/reference/datamodel.html#invoking-descriptors page:
"""
Super Binding
If a is an instance of super, then the binding super(B, obj).m() searches
obj.__class__.__mro__ for the base class A immediately preceding B and then
invokes the descriptor with the call: A.__dict__['m'].__get__(obj,
obj.__class__).
"""
...introduces the method *call* (".m()") which AFAIK has nothing to do with the
actual matter of the description (attribute resolution).
Also, the "If *a* is an instance of super" fragment is strange, as *a* is not
used in the following sentences at all.
I believe the description should be:
"""
Super Binding
If binding to a super instance, super(B, obj).x searches
obj.__class__.__mro__ for the base class A immediately preceding B and then
invokes the descriptor with the call: A.__dict__['x'].__get__(obj,
obj.__class__).
"""
(using 'x' as the attribute name, as for the other kinds of binding).
***
2. Also, in some earlier fragment of the same page:
"""
Direct Call
The simplest and least common call is when user code directly invokes a
descriptor method: x.__get__(a).
"""
The call x.__get__(a) without the second argument seems to be wrong if __get__
is implemented according to the specification "object.__get__(self, instance,
owner)" from the same documentation page.
----------
assignee: docs@python
components: Documentation
messages: 212035
nosy: docs@python, zuo
priority: normal
severity: normal
status: open
title: Misleading examples indDescriptor protocol documentation
versions: Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4
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Python tracker <[email protected]>
<http://bugs.python.org/issue20751>
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