Finished the "porting to 3.0" section. Had to add a label to

howto/cporting.rst.
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Guido van Rossum 2008-12-02 22:58:36 +00:00
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.. highlightlang:: c
.. _cporting-howto:
********************************
Porting Extension Modules to 3.0
********************************

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Library Changes
===============
Due to time constraints, this document does not exhaustively cover
the very extensive changes to the library.
XXX Brief overview of what's changed in the library.
* :pep:`3108`: stdlib reorganization.
@ -778,16 +781,35 @@ XXX Some of the more notable changes are:
Porting To Python 3.0
=====================
This section lists previously described changes that may require
changes to your code:
For porting existing Python 2.5 or 2.6 source code to Python 3.0, the
best strategy is the following:
* Everything is all in the details!
0. (Prerequisite:) Start with excellent test coverage.
* Developers can include :file:`intobject.h` after :file:`Python.h` for
some ``PyInt_`` aliases.
1. Port to Python 2.6. This should be no more work than the average
port from Python 2.x to Python 2.(x+1). Make sure all your tests
pass.
* XXX Mention 2to3.
2. (Still using 2.6:) Turn on the :option:`-3` command line switch.
This enables warnings about features that will be removed (or
change) in 3.0. Run your test suite again, and fix code that you
get warnings about until there are no warnings left, and all your
tests still pass.
* XXX Reference external doc about porting extensions?
3. Run the ``2to3`` source-to-source translator over your source code
tree. (See :ref:`2to3-reference` for more on this tool.) Run the
result of the translation under Python 3.0. Manually fix up any
remaining issues, fixing problems until all tests pass again.
It is not recommended to try to write source code that runs unchanged
under both Python 2.6 and 3.0; you'd have to use a very contorted
coding style, e.g. avoiding :keyword:`print` statements, metaclasses,
and much more. If you are maintaining a library that needs to support
both Python 2.6 and Python 3.0, the best approach is to modify step 3
above by editing the 2.6 version of the source code and running the
``2to3`` translator again, rather than editing the 3.0 version of the
source code.
For porting C extensions to Python 3.0, please see :ref:`cporting-howto`.
.. ======================================================================