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authorLarry Hastings <larry@hastings.org>2012-02-28 23:17:23 (GMT)
committerLarry Hastings <larry@hastings.org>2012-02-28 23:17:23 (GMT)
commit0555cde98d37d3012fbed20a91f6afdacbf79523 (patch)
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parenta6bdfd1fa93ef07f4217fe4048c7a03d405f577e (diff)
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Issue #13086: Update howto/cporting.rst to discuss "Python 3" instead of "3.0".
-rw-r--r--Doc/howto/cporting.rst73
1 files changed, 40 insertions, 33 deletions
diff --git a/Doc/howto/cporting.rst b/Doc/howto/cporting.rst
index 7ef7537..98db9dd 100644
--- a/Doc/howto/cporting.rst
+++ b/Doc/howto/cporting.rst
@@ -2,27 +2,28 @@
.. _cporting-howto:
-********************************
-Porting Extension Modules to 3.0
-********************************
+*************************************
+Porting Extension Modules to Python 3
+*************************************
:author: Benjamin Peterson
.. topic:: Abstract
- Although changing the C-API was not one of Python 3.0's objectives, the many
- Python level changes made leaving 2.x's API intact impossible. In fact, some
- changes such as :func:`int` and :func:`long` unification are more obvious on
- the C level. This document endeavors to document incompatibilities and how
- they can be worked around.
+ Although changing the C-API was not one of Python 3's objectives,
+ the many Python-level changes made leaving Python 2's API intact
+ impossible. In fact, some changes such as :func:`int` and
+ :func:`long` unification are more obvious on the C level. This
+ document endeavors to document incompatibilities and how they can
+ be worked around.
Conditional compilation
=======================
-The easiest way to compile only some code for 3.0 is to check if
-:c:macro:`PY_MAJOR_VERSION` is greater than or equal to 3. ::
+The easiest way to compile only some code for Python 3 is to check
+if :c:macro:`PY_MAJOR_VERSION` is greater than or equal to 3. ::
#if PY_MAJOR_VERSION >= 3
#define IS_PY3K
@@ -35,7 +36,7 @@ conditional blocks.
Changes to Object APIs
======================
-Python 3.0 merged together some types with similar functions while cleanly
+Python 3 merged together some types with similar functions while cleanly
separating others.
@@ -43,14 +44,14 @@ str/unicode Unification
-----------------------
-Python 3.0's :func:`str` (``PyString_*`` functions in C) type is equivalent to
-2.x's :func:`unicode` (``PyUnicode_*``). The old 8-bit string type has become
-:func:`bytes`. Python 2.6 and later provide a compatibility header,
+Python 3's :func:`str` (``PyString_*`` functions in C) type is equivalent to
+Python 2's :func:`unicode` (``PyUnicode_*``). The old 8-bit string type has
+become :func:`bytes`. Python 2.6 and later provide a compatibility header,
:file:`bytesobject.h`, mapping ``PyBytes`` names to ``PyString`` ones. For best
-compatibility with 3.0, :c:type:`PyUnicode` should be used for textual data and
+compatibility with Python 3, :c:type:`PyUnicode` should be used for textual data and
:c:type:`PyBytes` for binary data. It's also important to remember that
-:c:type:`PyBytes` and :c:type:`PyUnicode` in 3.0 are not interchangeable like
-:c:type:`PyString` and :c:type:`PyUnicode` are in 2.x. The following example
+:c:type:`PyBytes` and :c:type:`PyUnicode` in Python 3 are not interchangeable like
+:c:type:`PyString` and :c:type:`PyUnicode` are in Python 2. The following example
shows best practices with regards to :c:type:`PyUnicode`, :c:type:`PyString`,
and :c:type:`PyBytes`. ::
@@ -94,10 +95,12 @@ and :c:type:`PyBytes`. ::
long/int Unification
--------------------
-In Python 3.0, there is only one integer type. It is called :func:`int` on the
-Python level, but actually corresponds to 2.x's :func:`long` type. In the
-C-API, ``PyInt_*`` functions are replaced by their ``PyLong_*`` neighbors. The
-best course of action here is using the ``PyInt_*`` functions aliased to
+Python 3 has only one integer type, :func:`int`. But it actually
+corresponds to Python 2's :func:`long` type--the :func:`int` type
+used in Python 2 was removed. In the C-API, ``PyInt_*`` functions
+are replaced by their ``PyLong_*`` equivalents.
+
+The best course of action here is using the ``PyInt_*`` functions aliased to
``PyLong_*`` found in :file:`intobject.h`. The abstract ``PyNumber_*`` APIs
can also be used in some cases. ::
@@ -120,10 +123,11 @@ can also be used in some cases. ::
Module initialization and state
===============================
-Python 3.0 has a revamped extension module initialization system. (See
-:pep:`3121`.) Instead of storing module state in globals, they should be stored
-in an interpreter specific structure. Creating modules that act correctly in
-both 2.x and 3.0 is tricky. The following simple example demonstrates how. ::
+Python 3 has a revamped extension module initialization system. (See
+:pep:`3121`.) Instead of storing module state in globals, they should
+be stored in an interpreter specific structure. Creating modules that
+act correctly in both Python 2 and Python 3 is tricky. The following
+simple example demonstrates how. ::
#include "Python.h"
@@ -223,15 +227,18 @@ If you're currently using CObjects, and you want to migrate to 3.1 or newer,
you'll need to switch to Capsules.
:c:type:`CObject` was deprecated in 3.1 and 2.7 and completely removed in
Python 3.2. If you only support 2.7, or 3.1 and above, you
-can simply switch to :c:type:`Capsule`. If you need to support 3.0 or
-versions of Python earlier than 2.7 you'll have to support both CObjects
-and Capsules.
+can simply switch to :c:type:`Capsule`. If you need to support Python 3.0,
+or versions of Python earlier than 2.7,
+you'll have to support both CObjects and Capsules.
+(Note that Python 3.0 is no longer supported, and it is not recommended
+for production use.)
The following example header file :file:`capsulethunk.h` may
-solve the problem for you;
-simply write your code against the :c:type:`Capsule` API, include
-this header file after ``"Python.h"``, and you'll automatically use CObjects
-in Python 3.0 or versions earlier than 2.7.
+solve the problem for you. Simply write your code against the
+:c:type:`Capsule` API and include this header file after
+:file:`Python.h`. Your code will automatically use Capsules
+in versions of Python with Capsules, and switch to CObjects
+when Capsules are unavailable.
:file:`capsulethunk.h` simulates Capsules using CObjects. However,
:c:type:`CObject` provides no place to store the capsule's "name". As a
@@ -266,5 +273,5 @@ Other options
If you are writing a new extension module, you might consider `Cython
<http://www.cython.org>`_. It translates a Python-like language to C. The
-extension modules it creates are compatible with Python 3.x and 2.x.
+extension modules it creates are compatible with Python 3 and Python 2.