Commit a92d1f50 authored by Antoine Pitrou's avatar Antoine Pitrou

Merged revisions 87188-87190,87192-87194 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/branches/py3k

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  r87188 | antoine.pitrou | 2010-12-12 19:25:25 +0100 (dim., 12 déc. 2010) | 3 lines

  Make this a warning and fix indentation
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  r87189 | antoine.pitrou | 2010-12-12 20:59:47 +0100 (dim., 12 déc. 2010) | 3 lines

  Better explain the buffer interface (hopefully)
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  r87190 | antoine.pitrou | 2010-12-12 21:01:43 +0100 (dim., 12 déc. 2010) | 3 lines

  Add link to the buffer protocol description from the memory description.
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  r87192 | antoine.pitrou | 2010-12-12 21:09:18 +0100 (dim., 12 déc. 2010) | 3 lines

  Remove redundant sentence, and fix markup
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  r87193 | antoine.pitrou | 2010-12-12 21:13:31 +0100 (dim., 12 déc. 2010) | 3 lines

  Fix heading level
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  r87194 | antoine.pitrou | 2010-12-12 21:17:29 +0100 (dim., 12 déc. 2010) | 3 lines

  Consistent ordering of availability statements
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parent 0101a3a8
......@@ -12,16 +12,32 @@ Buffer Protocol
.. index::
single: buffer interface
Python objects implemented in C can export a "buffer interface." These
functions can be used by an object to expose its data in a raw, byte-oriented
format. Clients of the object can use the buffer interface to access the
object data directly, without needing to copy it first.
Certain objects available in Python wrap access to an underlying memory
array or *buffer*. Such objects include the built-in :class:`bytes` and
:class:`bytearray`, and some extension types like :class:`array.array`.
Third-party libraries may define their own types for special purposes, such
as image processing or numeric analysis.
Examples of objects that support the buffer interface are :class:`bytes`,
:class:`bytearray` and :class:`array.array`. The bytes and bytearray objects
exposes their bytes contents in the buffer interface's byte-oriented form.
An :class:`array.array` can also expose its contents, but it should be noted
that array elements may be multi-byte values.
While each of these types have their own semantics, they share the common
characteristic of being backed by a possibly large memory buffer. It is
then desireable, in some situations, to access that buffer directly and
without intermediate copying.
Python provides such a facility at the C level in the form of the *buffer
protocol*. This protocol has two sides:
.. index:: single: PyBufferProcs
- on the producer side, a type can export a "buffer interface" which allows
objects of that type to expose information about their underlying buffer.
This interface is described in the section :ref:`buffer-structs`;
- on the consumer side, several means are available to obtain a pointer to
the raw underlying data of an object (for example a method parameter).
Simple objects such as :class:`bytes` and :class:`bytearray` expose their
underlying buffer in byte-oriented form. Other forms are possible; for example,
the elements exposed by a :class:`array.array` can be multi-byte values.
An example consumer of the buffer interface is the :meth:`~io.BufferedIOBase.write`
method of file objects: any object that can export a series of bytes through
......@@ -44,12 +60,6 @@ isn't needed anymore. Failure to do so could lead to various issues such as
resource leaks.
.. index:: single: PyBufferProcs
How the buffer interface is exposed by a type object is described in the
section :ref:`buffer-structs`, under the description for :ctype:`PyBufferProcs`.
The buffer structure
====================
......
......@@ -1193,7 +1193,7 @@ Buffer Object Structures
.. sectionauthor:: Benjamin Peterson
The buffer interface exports a model where an object can expose its internal
The :ref:`buffer interface <bufferobjects>` exports a model where an object can expose its internal
data.
If an object does not export the buffer interface, then its :attr:`tp_as_buffer`
......
......@@ -227,7 +227,7 @@ applications should use string objects to access all files.
*start* defaults to :attr:`os.curdir`.
Availability: Windows, Unix.
Availability: Unix, Windows.
.. function:: samefile(path1, path2)
......
......@@ -2081,9 +2081,9 @@ An example of dictionary view usage::
memoryview Types
================
:class:`memoryview`\s allow Python code to access the internal data of an object
that supports the buffer protocol without copying. Memory can be interpreted as
simple bytes or complex data structures.
:class:`memoryview` objects allow Python code to access the internal data
of an object that supports the :ref:`buffer protocol <bufferobjects>` without
copying. Memory is generally interpreted as simple bytes.
.. class:: memoryview(obj)
......@@ -2203,12 +2203,9 @@ Context Manager Types
single: protocol; context management
Python's :keyword:`with` statement supports the concept of a runtime context
defined by a context manager. This is implemented using two separate methods
defined by a context manager. This is implemented using a pair of methods
that allow user-defined classes to define a runtime context that is entered
before the statement body is executed and exited when the statement ends.
The :dfn:`context management protocol` consists of a pair of methods that need
to be provided for a context manager object to define a runtime context:
before the statement body is executed and exited when the statement ends:
.. method:: contextmanager.__enter__()
......@@ -2256,9 +2253,9 @@ decimal arithmetic context. The specific types are not treated specially beyond
their implementation of the context management protocol. See the
:mod:`contextlib` module for some examples.
Python's :term:`generator`\s and the ``contextlib.contextmanager`` :term:`decorator`
Python's :term:`generator`\s and the :class:`contextlib.contextmanager` decorator
provide a convenient way to implement these protocols. If a generator function is
decorated with the ``contextlib.contextmanager`` decorator, it will return a
decorated with the :class:`contextlib.contextmanager` decorator, it will return a
context manager implementing the necessary :meth:`__enter__` and
:meth:`__exit__` methods, rather than the iterator produced by an undecorated
generator function.
......
......@@ -5,12 +5,12 @@
:synopsis: Regression tests package containing the testing suite for Python.
.. sectionauthor:: Brett Cannon <brett@python.org>
.. note::
The :mod:`test` package is meant for internal use by Python only. It is
documented for the benefit of the core developers of Python. Any use of
this package outside of Python's standard library is discouraged as code
mentioned here can change or be removed without notice between releases of
Python.
.. warning::
The :mod:`test` package is meant for internal use by Python only. It is
documented for the benefit of the core developers of Python. Any use of
this package outside of Python's standard library is discouraged as code
mentioned here can change or be removed without notice between releases of
Python.
The :mod:`test` package contains all regression tests for Python as well as the
......
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