[issue31735] Documentation incorrectly states how descriptors are invoked

Raymond Hettinger added the comment: > it should have > > d.__get__(obj, type(obj)) instead of d.__get__(obj) The objtype argument is optional as shown in all of the examples. The call from object.__getattribute__() always passes in both parameters, even though only the first is required.

[issue31735] Documentation incorrectly states how descriptors are invoked

Change by Irit Katriel : -- versions: +Python 3.10, Python 3.11, Python 3.9 -Python 2.7, Python 3.4, Python 3.5, Python 3.6, Python 3.7, Python 3.8 ___ Python tracker ___

[issue31735] Documentation incorrectly states how descriptors are invoked

Change by Raymond Hettinger : -- assignee: docs@python -> rhettinger ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubs

[issue31735] Documentation incorrectly states how descriptors are invoked

Irit Katriel added the comment: See also Issue20751 -- nosy: +iritkatriel, rhettinger ___ Python tracker ___ ___ Python-bugs-list m

[issue31735] Documentation incorrectly states how descriptors are invoked

Henk-Jaap Wagenaar added the comment: I do think though that "If d defines the method __get__(), then d.__get__(obj) is invoked according to the precedence rules listed below." seems to contain a mistake in that it should have d.__get__(obj, type(obj)) instead of d.__get__(obj) --

[issue31735] Documentation incorrectly states how descriptors are invoked

Henk-Jaap Wagenaar added the comment: "We know this doesn't happen because nothing is printed to stdout." Try running Obj().d, you will get output. Obj.d does not work because it is on a *class*, and so it runs, per the docs: 'Obj.__dict__['d'].__get__(None, Obj)' whereas you consider runnin

[issue31735] Documentation incorrectly states how descriptors are invoked

Paul Pinterits added the comment: If we take this class: class Obj: @property def d(self): print('called') And we access Obj.d: _ = Obj.d According to the docs, the following should happen: # obj.d looks up d in the dictionary of obj d = Obj.__dict__['d'] # If d defines the

[issue31735] Documentation incorrectly states how descriptors are invoked

Paul Pinterits added the comment: I'm aware that descriptors have to exist on the class in order to work. The point is that the documentation states "If d defines the method __get__(), then d.__get__(obj) is invoked" (where d is obj.d), which is simply not true. -- __

[issue31735] Documentation incorrectly states how descriptors are invoked

Henk-Jaap Wagenaar added the comment: You get what you should get: when you print obj.d, Obj.d, you will get: which is exactly what you expect: - in the first case, you assigned a property object to the dictionary at obj.__dict__, so that's what you get back when you run obj.d. - you defined

[issue31735] Documentation incorrectly states how descriptors are invoked

New submission from Paul Pinterits : The [descriptor howto](https://docs.python.org/3/howto/descriptor.html#invoking-descriptors) states: "For example, obj.d looks up d in the dictionary of obj. If d defines the method __get__(), then d.__get__(obj) is invoked [...]" This is not true - the d