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Mention pickle protocol 4, and some tweaks.

This commit is contained in:
Antoine Pitrou 2013-12-07 01:05:57 +01:00
parent 9858e8b98d
commit 9bcb1127f1
1 changed files with 18 additions and 7 deletions
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Doc/library/pickle.rst
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@ -94,6 +94,9 @@ There are fundamental differences between the pickle protocols and
The :mod:`json` module: a standard library module allowing JSON
serialization and deserialization.
.. _pickle-protocols:
Data stream format
------------------
@ -125,10 +128,15 @@ There are currently 4 different protocols which can be used for pickling.
efficient pickling of :term:`new-style class`\es. Refer to :pep:`307` for
information about improvements brought by protocol 2.
* Protocol version 3 was added in Python 3. It has explicit support for
* Protocol version 3 was added in Python 3.0. It has explicit support for
:class:`bytes` objects and cannot be unpickled by Python 2.x. This is
the default as well as the current recommended protocol; use it whenever
possible.
the default protocol, and the recommended protocol when compatibility with
other Python 3 versions is required.
* Protocol version 4 was added in Python 3.4. It adds support for very large
objects, pickling more kinds of objects, and some data format
optimizations. Refer to :pep:`3154` for information about improvements
brought by protocol 4.
.. note::
Serialization is a more primitive notion than persistence; although
@ -156,13 +164,16 @@ The :mod:`pickle` module provides the following constants:
.. data:: HIGHEST_PROTOCOL
The highest protocol version available. This value can be passed as a
*protocol* value.
An integer, the highest :ref:`protocol version <pickle-protocols>`
available. This value can be passed as a *protocol* value to functions
:func:`dump` and :func:`dumps` as well as the :class:`Pickler`
constructor.
.. data:: DEFAULT_PROTOCOL
The default protocol used for pickling. May be less than HIGHEST_PROTOCOL.
Currently the default protocol is 3, a new protocol designed for Python 3.0.
An integer, the default :ref:`protocol version <pickle-protocols>` used
for pickling. May be less than :data:`HIGHEST_PROTOCOL`. Currently the
default protocol is 3, a new protocol designed for Python 3.0.
The :mod:`pickle` module provides the following functions to make the pickling