cpython/Misc
Łukasz Langa b83861f026
bpo-42073: allow classmethod to wrap other classmethod-like descriptors (#27115)
Patch by Erik Welch.

bpo-19072 (#8405) allows `classmethod` to wrap other descriptors, but this does
not work when the wrapped descriptor mimics classmethod.  The current PR fixes
this.

In Python 3.8 and before, one could create a callable descriptor such that this
works as expected (see Lib/test/test_decorators.py for examples):
```python
class A:
    @myclassmethod
    def f1(cls):
        return cls

    @classmethod
    @myclassmethod
    def f2(cls):
        return cls
```
In Python 3.8 and before, `A.f2()` return `A`. Currently in Python 3.9, it
returns `type(A)`.  This PR make `A.f2()` return `A` again.

As of #8405, classmethod calls `obj.__get__(type)` if `obj` has `__get__`.
This allows one to chain `@classmethod` and `@property` together.  When
using classmethod-like descriptors, it's the second argument to `__get__`--the
owner or the type--that is important, but this argument is currently missing.
Since it is None, the "owner" argument is assumed to be the type of the first
argument, which, in this case, is wrong (we want `A`, not `type(A)`).

This PR updates classmethod to call `obj.__get__(type, type)` if `obj` has
`__get__`.

Co-authored-by: Erik Welch <erik.n.welch@gmail.com>
2021-07-15 15:16:19 +02:00
..
NEWS.d bpo-42073: allow classmethod to wrap other classmethod-like descriptors (#27115) 2021-07-15 15:16:19 +02:00
ACKS [Enum] improve test, add andrei kulakov to ACKS (GH-26726) 2021-06-15 11:38:15 -07:00
coverity_model.c bpo-35808: Retire pgen and use pgen2 to generate the parser (GH-11814) 2019-03-01 15:34:44 -08:00
gdbinit gdbinit: Use proper define syntax (GH-19557) 2020-04-23 05:49:26 -07:00
HISTORY Fix typos mostly in comments, docs and test names (GH-15209) 2019-08-30 16:21:19 -04:00
indent.pro
Porting bpo-30737: Update DevGuide links to new URL (GH-3228) 2017-08-30 09:37:43 -07:00
python-config.in bpo-38468 : Refactor python-config (#16749) 2019-10-15 11:18:47 -03:00
python-config.sh.in bpo-37925: Mention --embed in python-config usage (GH-15458) 2019-08-26 23:45:36 +02:00
python-embed.pc.in bpo-36721: Add --embed option to python-config (GH-13500) 2019-05-23 03:30:23 +02:00
python-wing3.wpr Mark files as executable that are meant as scripts. (GH-15354) 2019-09-09 07:16:33 -07:00
python-wing4.wpr Mark files as executable that are meant as scripts. (GH-15354) 2019-09-09 07:16:33 -07:00
python-wing5.wpr Mark files as executable that are meant as scripts. (GH-15354) 2019-09-09 07:16:33 -07:00
python.man bpo-43862: Enhance -W cmdline option documentation (GH-25439) 2021-04-16 19:12:14 +02:00
python.pc.in bpo-36721: Add --embed option to python-config (GH-13500) 2019-05-23 03:30:23 +02:00
README bpo-32159: Revert Misc/svnmap.txt (#4639) 2017-11-29 18:58:33 +01:00
README.AIX bpo-42087: Remove support for AIX 5.3 and below (GH-22830) 2020-11-16 16:16:10 +01:00
README.coverity
README.valgrind bpo-18859: Document --with-valgrind option in README.valgrind (#10591) 2018-11-20 12:10:49 +01:00
requirements-test.txt Update tzdata to 2020.3 (GH-22856) 2020-10-21 06:40:43 -07:00
SpecialBuilds.txt bpo-43774: Remove unused PYMALLOC_DEBUG macro (GH-25711) 2021-04-29 10:47:47 +02:00
stable_abi.txt bpo-39947: Remove old private trashcan C API functions (GH-26869) 2021-06-23 15:51:47 +02:00
svnmap.txt bpo-32159: Revert Misc/svnmap.txt (#4639) 2017-11-29 18:58:33 +01:00
valgrind-python.supp bpo-35561: Supress valgrind false alarm on epoll_ctl(event) (GH-18060) 2020-01-19 23:38:37 +01:00
vgrindefs

Python Misc subdirectory
========================

This directory contains files that wouldn't fit in elsewhere.  Some
documents are only of historic importance.

Files found here
----------------

ACKS                    Acknowledgements
gdbinit                 Handy stuff to put in your .gdbinit file, if you use gdb
HISTORY                 News from previous releases -- oldest last
indent.pro              GNU indent profile approximating my C style
NEWS                    News for this release (for some meaning of "this")
Porting                 Mini-FAQ on porting to new platforms
python-config.in        Python script template for python-config
python.man              UNIX man page for the python interpreter
python.pc.in            Package configuration info template for pkg-config
python-wing*.wpr        Wing IDE project file
README                  The file you're reading now
README.AIX              Information about using Python on AIX
README.coverity         Information about running Coverity's Prevent on Python
README.valgrind         Information for Valgrind users, see valgrind-python.supp
SpecialBuilds.txt       Describes extra symbols you can set for debug builds
svnmap.txt              Map of old SVN revs and branches to hg changeset ids,
                        help history-digging
valgrind-python.supp    Valgrind suppression file, see README.valgrind
vgrindefs               Python configuration for vgrind (a generic pretty printer)