[New-bugs-announce] [issue30463] Add __slots__ to ABC convenience class

Aaron Hall report at bugs.python.org
Wed May 24 16:41:17 EDT 2017

New submission from Aaron Hall:

We have __slots__ with other ABC's, see http://bugs.python.org/issue11333 and http://bugs.python.org/issue21421.

There are no downsides to having empty slots on a non-instantiable class, but it does give the option of denying __dict__ creation for subclassers. 

The possibility of breaking is for someone using __slots__ but relying on __dict__ creation in a subclass - they will have to explicitly add "__dict__" to __slots__. Since we have added __slots__ to other ABC's, 

I will provide a PR soon on this. Diff should look like this (in Lib/abc.py):

class ABC(metaclass=ABCMeta):
    """Helper class that provides a standard way to create an ABC using
- pass
+ __slots__ = ()

(I also want to add a test for this, and ensure other ABC's also have this if they don't.)

messages: 294389
nosy: Aaron Hall
priority: normal
severity: normal
status: open
title: Add __slots__ to ABC convenience class

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