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Title: Flag inappropriate uses of callable class attributes
Type: enhancement Stage: resolved
Components: Interpreter Core Versions: Python 3.3
Status: closed Resolution: out of date
Dependencies: Superseder:
Assigned To: Nosy List: BreamoreBoy, Trundle, alex, daniel.urban, eckhardt, eric.araujo, eric.snow, gvanrossum, ncoghlan, twouters
Priority: normal Keywords: patch

Created on 2011-03-11 19:22 by twouters, last changed 2022-04-11 14:57 by admin. This issue is now closed.

File name Uploaded Description Edit
nonmethod-warn.diff twouters, 2011-03-17 17:30 review
Messages (6)
msg130606 - (view) Author: Thomas Wouters (twouters) * (Python committer) Date: 2011-03-11 19:22
As discussed at the language summit at PyCon 2011, some code takes some liberties with setting class attributes to callable objects, like CFunctions, that (C)Python does not turn into methods. This is problematic because 1) CPython can't then turn that CFunction into a regular function, and 2) other implementations have to specialcase the builtins to emulate the behaviour.

This patch adds a warning when a non-descriptor, non-class callable attribute is accessed in a context that would have fired the descriptor. It also fixes a bunch of these warnings that show up when running the testsuite. Some of these warnings are obviously (to me) incorrect code  -- like the io testsuite, which uses staticmethod around but not, or the encoding classes that use an encode function from an extension module as a class attribute. Some of the warnings are debatable, but have an obvious fix (wrap in staticmethod.) Some could be considered false-positives because they actually use (what amounts to) a a bound instance method as a class attribute (for example, re.compile('...').match.)

The patch is still a work in progress, I'm just uploading to start the discussion sooner rather than later.
msg130610 - (view) Author: Éric Araujo (eric.araujo) * (Python committer) Date: 2011-03-11 20:24
Don’t forget to remove the comments in codecs that are made obsolete by your changes.
msg130617 - (view) Author: Guido van Rossum (gvanrossum) * (Python committer) Date: 2011-03-11 21:41
This should not reuse DeprecationWarning but instead introduce a different warning, e.g. CompatibilityWarning.
msg131270 - (view) Author: Thomas Wouters (twouters) * (Python committer) Date: 2011-03-17 17:30
New version of the patch; instead of triggering at attribute *access*, this just checks when creating types and in type_setattro. It also makes the warning a newly added CompatibilityWarning. Also, instead of warning for all non-descriptors, it now only warns for PyCFunctionObjects that do not have a __self__ set, or of which __self__ is a module. (The reason for the latter being the new-ish behaviour of functions defined in modules in C getting passed something as __self__, defaulting to the module.) I've removed a few staticmethod calls from cases that do not trigger the new warning.

This patch still lacks tests and doc updates, but I'm uploading right now because the sprints apparently lose internet soonish.
msg140265 - (view) Author: Éric Araujo (eric.araujo) * (Python committer) Date: 2011-07-13 15:14
Hi Thomas, could you give us a status update?  Maybe I can help with tests or docs?
msg222712 - (view) Author: Mark Lawrence (BreamoreBoy) * Date: 2014-07-10 23:25
This issue is referred to from #11455.
Date User Action Args
2022-04-11 14:57:14adminsetgithub: 55679
2017-05-22 19:27:35twouterssetstatus: open -> closed
resolution: out of date
stage: resolved
2014-07-10 23:25:07BreamoreBoysetnosy: + BreamoreBoy
messages: + msg222712
2013-06-05 04:33:38ncoghlansetnosy: + ncoghlan
2013-02-25 16:23:49eckhardtsetnosy: + eckhardt
2011-07-13 16:14:12eric.snowsetnosy: + eric.snow
2011-07-13 15:14:48eric.araujosetmessages: + msg140265
2011-03-17 17:31:02twouterssetfiles: - nonmethod-warn-nongit.diff
nosy: gvanrossum, twouters, eric.araujo, alex, Trundle, daniel.urban
2011-03-17 17:30:43twouterssetfiles: + nonmethod-warn.diff
nosy: gvanrossum, twouters, eric.araujo, alex, Trundle, daniel.urban
messages: + msg131270
2011-03-11 21:41:12gvanrossumsetnosy: + gvanrossum
messages: + msg130617
2011-03-11 20:26:27twouterssetfiles: - nonmethod-warn-nongit.diff
nosy: twouters, eric.araujo, alex, Trundle, daniel.urban
2011-03-11 20:26:18twouterssetfiles: + nonmethod-warn-nongit.diff
nosy: twouters, eric.araujo, alex, Trundle, daniel.urban
2011-03-11 20:24:02eric.araujosetnosy: + eric.araujo
messages: + msg130610
2011-03-11 20:22:13twouterssetfiles: - nonmethod-warn.diff
nosy: twouters, alex, Trundle, daniel.urban
2011-03-11 20:21:58twouterssetfiles: + nonmethod-warn-nongit.diff
nosy: twouters, alex, Trundle, daniel.urban
2011-03-11 19:57:36daniel.urbansetnosy: + daniel.urban
2011-03-11 19:25:49alexsetnosy: + alex
2011-03-11 19:23:25Trundlesetnosy: + Trundle
2011-03-11 19:22:07twouterscreate