[Python-Dev] cpython: Close #14588: added a PEP 3115 compliant dynamic type creation mechanism

[Georg Brandl]

Am 19.05.2012 18:34, schrieb nick.coghlan:

> diff --git a/Doc/library/types.rst b/Doc/library/types.rst
> --- a/Doc/library/types.rst
> +++ b/Doc/library/types.rst
> @@ -1,5 +1,5 @@
> -:mod:`types` --- Names for built-in types
> -=========================================
> +:mod:`types` --- Dynamic type creation and names for built-in types
> +===================================================================
>  
>  .. module:: types
>     :synopsis: Names for built-in types.
> @@ -8,20 +8,69 @@
>  
>  --------------
>  
> -This module defines names for some object types that are used by the standard
> +This module defines utility function to assist in dynamic creation of
> +new types.
> +
> +It also defines names for some object types that are used by the standard
>  Python interpreter, but not exposed as builtins like :class:`int` or
> -:class:`str` are.  Also, it does not include some of the types that arise
> -transparently during processing such as the ``listiterator`` type.
> +:class:`str` are.
>  
> -Typical use is for :func:`isinstance` or :func:`issubclass` checks.
>  
> -The module defines the following names:
> +Dynamic Type Creation
> +---------------------
> +
> +.. function:: new_class(name, bases=(), kwds=None, exec_body=None)
> +
> +   Creates a class object dynamically using the appropriate metaclass.
> +
> +   The arguments are the components that make up a class definition: the
> +   class name, the base classes (in order), the keyword arguments (such as
> +   ``metaclass``) and the callback function to populate the class namespace.
> +
> +   The *exec_body* callback should accept the class namespace as its sole
> +   argument and update the namespace directly with the class contents.
> +
> +.. function:: prepare_class(name, bases=(), kwds=None)
> +
> +   Calculates the appropriate metaclass and creates the class namespace.
> +
> +   The arguments are the components that make up a class definition: the
> +   class name, the base classes (in order) and the keyword arguments (such as
> +   ``metaclass``).
> +
> +   The return value is a 3-tuple: ``metaclass, namespace, kwds``
> +
> +   *metaclass* is the appropriate metaclass
> +   *namespace* is the prepared class namespace
> +   *kwds* is an updated copy of the passed in *kwds* argument with any
> +   ``'metaclass'`` entry removed. If no *kwds* argument is passed in, this
> +   will be an empty dict.
> +
> +
> +.. seealso::
> +
> +   :pep:`3115` - Metaclasses in Python 3000
> +      Introduced the ``__prepare__`` namespace hook
> +
> +

Should have versionadded.

Georg