From: Mariatta Date: Sat, 10 Jun 2017 03:36:28 +0000 (-0700) Subject: bpo-30266: support "= None" pattern in AbstractContextManager (GH-1448) (GH-2054) X-Git-Tag: v3.6.2rc1~68 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=753422f6e32e13d96319b090788f0474f1e21fc4;p=python bpo-30266: support "= None" pattern in AbstractContextManager (GH-1448) (GH-2054) contextlib.AbstractContextManager now supports anti-registration by setting __enter__ = None or __exit__ = None, following the pattern introduced in bpo-25958.. (cherry picked from commit 57161aac5eb9bcb0b43e551a1937ff0a84c1ec52) --- diff --git a/Lib/contextlib.py b/Lib/contextlib.py index 5e47054954..6fcba9c7d2 100644 --- a/Lib/contextlib.py +++ b/Lib/contextlib.py @@ -1,6 +1,7 @@ """Utilities for with-statement contexts. See PEP 343.""" import abc import sys +import _collections_abc from collections import deque from functools import wraps @@ -25,9 +26,7 @@ class AbstractContextManager(abc.ABC): @classmethod def __subclasshook__(cls, C): if cls is AbstractContextManager: - if (any("__enter__" in B.__dict__ for B in C.__mro__) and - any("__exit__" in B.__dict__ for B in C.__mro__)): - return True + return _collections_abc._check_methods(C, "__enter__", "__exit__") return NotImplemented diff --git a/Lib/test/test_contextlib.py b/Lib/test/test_contextlib.py index b1a467d952..2301f759d8 100644 --- a/Lib/test/test_contextlib.py +++ b/Lib/test/test_contextlib.py @@ -44,6 +44,16 @@ class TestAbstractContextManager(unittest.TestCase): self.assertTrue(issubclass(DefaultEnter, AbstractContextManager)) + class NoEnter(ManagerFromScratch): + __enter__ = None + + self.assertFalse(issubclass(NoEnter, AbstractContextManager)) + + class NoExit(ManagerFromScratch): + __exit__ = None + + self.assertFalse(issubclass(NoExit, AbstractContextManager)) + class ContextManagerTestCase(unittest.TestCase): diff --git a/Misc/NEWS b/Misc/NEWS index 213a6e9c2f..e6517695a6 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -96,6 +96,10 @@ Library - bpo-30048: Fixed ``Task.cancel()`` can be ignored when the task is running coroutine and the coroutine returned without any more ``await``. +- bpo-30266: contextlib.AbstractContextManager now supports anti-registration + by setting __enter__ = None or __exit__ = None, following the pattern + introduced in bpo-25958. Patch by Jelle Zijlstra. + - bpo-30298: Weaken the condition of deprecation warnings for inline modifiers. Now allowed several subsequential inline modifiers at the start of the pattern (e.g. ``'(?i)(?s)...'``). In verbose mode whitespaces and comments