[New-bugs-announce] [issue12773] classes should have mutable docstrings

[Eric Snow]

New submission from Eric Snow <ericsnowcurrently at gmail.com>:

Apparently docstrings for classes are immutable:

>>> class X:
...     "some doc"
...
>>> X.__doc__
'some doc'
>>> X.__doc__ = "another doc"
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
AttributeError: attribute '__doc__' of 'type' objects is not writable

That is on 3.3, but apparently it's the case all the way back to 2.2.
I mentioned this on python-list and several people indicated that it
should be an unnecessary restriction [1].  I also found that this only impacts classes that do not have a custom metaclass.

Regardless, it looks like this is something that no one has take the time to address but would be nice to have done [2][3].  I found that the type_getset for __doc__ does not have a getter:

http://hg.python.org/cpython/file/default/Objects/typeobject.c#l634

I have attached a patch that adds one and fixes the problem.  "make test" passed after the fix.


[1] http://mail.python.org/pipermail/python-list/2011-June/1274079.html
[2] http://mail.python.org/pipermail/python-ideas/2011-June/010462.html
[3] http://mail.python.org/pipermail/python-ideas/2011-August/011185.html

----------
components: Interpreter Core
files: mutable_class_docstrings.diff
keywords: patch
messages: 142287
nosy: eric.snow, michael.foord, ncoghlan
priority: normal
severity: normal
status: open
title: classes should have mutable docstrings
type: behavior
versions: Python 3.3
Added file: http://bugs.python.org/file22925/mutable_class_docstrings.diff

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<http://bugs.python.org/issue12773>
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