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Wrong function calls and referring to not removed concepts in descriptor HowTo (documentation) #69621
Description
| BPO | 25435 |
|---|---|
| Nosy | @rhettinger, @dholth, @vadmium, @eryksun, @marco-buttu, @Mariatta |
| Files |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields:
assignee = 'https://github.com/rhettinger'
closed_at = <Date 2019-08-29.06:46:53.357>
created_at = <Date 2015-10-18.18:49:49.065>
labels = ['3.7', 'docs']
title = 'Wrong function calls and referring to not removed concepts in descriptor HowTo (documentation)'
updated_at = <Date 2019-08-29.06:46:53.356>
user = 'https://bugs.python.org/DavidBecher'bugs.python.org fields:
activity = <Date 2019-08-29.06:46:53.356>
actor = 'rhettinger'
assignee = 'rhettinger'
closed = True
closed_date = <Date 2019-08-29.06:46:53.357>
closer = 'rhettinger'
components = ['Documentation']
creation = <Date 2015-10-18.18:49:49.065>
creator = 'David Becher'
dependencies = []
files = ['40812']
hgrepos = []
issue_num = 25435
keywords = []
message_count = 12.0
messages = ['253159', '253165', '253168', '253202', '270007', '270014', '293162', '293163', '293237', '293252', '302921', '350735']
nosy_count = 8.0
nosy_names = ['rhettinger', 'dholth', 'docs@python', 'martin.panter', 'eryksun', 'marco.buttu', 'David Becher', 'Mariatta']
pr_nums = []
priority = 'normal'
resolution = 'out of date'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue25435'
versions = ['Python 3.5', 'Python 3.6', 'Python 3.7']
Activity
DavidBecher commentedon Oct 18, 2015
Since Python 3 removed unbound methods, I found some references using the old terminology in this HowTo about descriptors (https://docs.python.org/3/howto/descriptor.html). Also, since unbound methods have been removed, the function call types.MethodType now only takes two arguments, namely the function to bind and the object to bind to. In the current documentation, however, the old function call with three arguments is still being used.
I made a pull request on github, then I realized that it is just a mirror repo. Attached you will see a patch file with some of the obvious changes that could me made to the document
vadmium commentedon Oct 19, 2015
Thanks for the patch. I left a few comments on the code review. I think the class is meant to represent a real function object, not a wrapper. And it would be good to update the following paragraphs about unbound methods.
Also, it looks like the rest of that page could do with some other updates. E.g. no need for explicit Function(object) base class, no need to mention that a method exists in Python 2.3, code could use @classmethod decorator syntax. But these are a slightly separate issues.
vadmium commentedon Oct 19, 2015
Also further up the page, “unbound methods . . . are . . . based on the descriptor protocol” is probably not really correct or useful. bpo-23702 is already open about mentioning unbound methods.
rhettinger commentedon Oct 20, 2015
I'll update this document to reflect the current state of the world.
dholth commentedon Jul 8, 2016
This bit me also. Is there other documentation for how many arguments MethodType() should take?
eryksun commentedon Jul 8, 2016
I'm surprised it's not documented for the types module:
https://docs.python.org/3.5/library/types.html#types.MethodType
At least the docstring has the parameters:
>>> print(types.MethodType.__doc__) method(function, instance) Create a bound instance method object.vadmium commentedon May 6, 2017
Raymond I suggest you unassign this and let others work on it.
rhettinger commentedon May 6, 2017
I will have a chance to work on this before long.
marco-buttu commentedon May 8, 2017
I also noticed that the howto differentiates between objects and classes:
"The details of invocation depend on whether obj is an object or a class."
I think it is misleading, because a class is actually an object. IMHO is better to differentiate between classes and non-classes objects:
"The details of invocation depend on whether obj is a class or not."
rhettinger commentedon May 8, 2017
This is only misleading *after* you know all the interesting details about Python and metaclasses. Prior to that, it is a reasonable and important distinction that I don't want to get lost in weasel words. The calls from object.__getattribute__ are different that those from type.__getattribute__. Likewise, data and non-data descriptors can only be described in terms of objects versus classes. Lastly, descriptors only work when stored in a class, if you store them in instances, they don't get invoked.
rhettinger commentedon Sep 25, 2017
I've just updated the section on unbound methods. I'll be working on a number of other improvements over the next few weeks and will incorporate the suggested changes where appropriate.
rhettinger commentedon Aug 29, 2019
This was fixed a long time ago.