[Python-Dev] cpython: Issue #16049: add abc.ABC helper class.

[Georg Brandl]

Am 13.12.2012 18:09, schrieb andrew.svetlov:
> http://hg.python.org/cpython/rev/9347869d1066
> changeset:   80840:9347869d1066
> user:        Andrew Svetlov <andrew.svetlov at gmail.com>
> date:        Thu Dec 13 19:09:33 2012 +0200
> summary:
>   Issue #16049: add abc.ABC helper class.
> 
> Patch by Bruno Dupuis.
> 
> files:
>   Doc/library/abc.rst  |  18 ++++++++++++++----
>   Lib/abc.py           |   6 ++++++
>   Lib/test/test_abc.py |  13 +++++++++++++
>   Misc/NEWS            |   3 +++
>   4 files changed, 36 insertions(+), 4 deletions(-)
> 
> 
> diff --git a/Doc/library/abc.rst b/Doc/library/abc.rst
> --- a/Doc/library/abc.rst
> +++ b/Doc/library/abc.rst
> @@ -12,9 +12,9 @@
>  --------------
>  
>  This module provides the infrastructure for defining :term:`abstract base
> -classes <abstract base class>` (ABCs) in Python, as outlined in :pep:`3119`; see the PEP for why this
> -was added to Python. (See also :pep:`3141` and the :mod:`numbers` module
> -regarding a type hierarchy for numbers based on ABCs.)
> +classes <abstract base class>` (ABCs) in Python, as outlined in :pep:`3119`;
> +see the PEP for why this was added to Python. (See also :pep:`3141` and the
> +:mod:`numbers` module regarding a type hierarchy for numbers based on ABCs.)
>  
>  The :mod:`collections` module has some concrete classes that derive from
>  ABCs; these can, of course, be further derived. In addition the
> @@ -23,7 +23,7 @@
>  hashable or a mapping.
>  
>  
> -This module provides the following class:
> +This module provides the following classes:
>  
>  .. class:: ABCMeta
>  
> @@ -127,6 +127,16 @@
>     available as a method of ``Foo``, so it is provided separately.
>  
>  
> +.. class:: ABC
> +
> +   A helper class that has :class:`ABCMeta` as metaclass. :class:`ABC` is the
> +   standard class to inherit from in order to create an abstract base class,
> +   avoiding sometimes confusing metaclass usage.
> +
> +   Note that :class:`ABC` type is still :class:`ABCMeta`, therefore inheriting
> +   from :class:`ABC` requires usual precautions regarding metaclasses usage
> +   as multiple inheritance may lead to metaclass conflicts.
> +

Needs a versionadded.

Georg