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| PEP: 229 | |
| Title: Using Distutils to Build Python | |
| Version: $Revision$ | |
| Last-Modified: $Date$ | |
| Author: A.M. Kuchling <amk@amk.ca> | |
| Status: Final | |
| Type: Standards Track | |
| Content-Type: text/x-rst | |
| Created: 16-Nov-2000 | |
| Post-History: | |
| Introduction | |
| ============ | |
| The ``Modules/Setup`` mechanism has some flaws: | |
| * People have to remember to uncomment bits of ``Modules/Setup`` in | |
| order to get all the possible modules. | |
| * Moving ``Setup`` to a new version of Python is tedious; new modules | |
| have been added, so you can't just copy the older version, but | |
| have to reconcile the two versions. | |
| * Users have to figure out where the needed libraries, such as | |
| ``zlib``, are installed. | |
| Proposal | |
| ======== | |
| Use the Distutils to build the modules that come with Python. | |
| The changes can be broken up into several pieces: | |
| 1. The Distutils needs some Python modules to be able to build | |
| modules. Currently I believe the minimal list is ``posix``, ``_sre``, | |
| and ``string``. | |
| These modules will have to be built before the Distutils can be | |
| used, so they'll simply be hardwired into ``Modules/Makefile`` and | |
| be automatically built. | |
| 2. A top-level setup.py script will be written that checks the | |
| libraries installed on the system and compiles as many modules | |
| as possible. | |
| 3. ``Modules/Setup`` will be kept and settings in it will override | |
| ``setup.py``'s usual behavior, so you can disable a module known | |
| to be buggy, or specify particular compilation or linker flags. | |
| However, in the common case where ``setup.py`` works correctly, | |
| everything in ``Setup`` will remain commented out. The other | |
| ``Setup.*`` become unnecessary, since nothing will be generating | |
| ``Setup`` automatically. | |
| The patch was checked in for Python 2.1, and has been subsequently | |
| modified. | |
| Implementation | |
| ============== | |
| Patch #102588 on SourceForge contains the proposed patch. | |
| Currently the patch tries to be conservative and to change as few | |
| files as possible, in order to simplify backing out the patch. | |
| For example, no attempt is made to rip out the existing build | |
| mechanisms. Such simplifications can wait for later in the beta | |
| cycle, when we're certain the patch will be left in, or they can | |
| wait for Python 2.2. | |
| The patch makes the following changes: | |
| * Makes some required changes to distutils/sysconfig (these will | |
| be checked in separately) | |
| * In the top-level ``Makefile.in``, the "sharedmods" target simply | |
| runs ``"./python setup.py build"``, and "sharedinstall" runs | |
| ``"./python setup.py install"``. The "clobber" target also deletes | |
| the ``build/`` subdirectory where Distutils puts its output. | |
| * ``Modules/Setup.config.in`` only contains entries for the ``gc`` and ``thread`` | |
| modules; the ``readline``, ``curses``, and ``db`` modules are removed because | |
| it's now ``setup.py``'s job to handle them. | |
| * ``Modules/Setup.dist`` now contains entries for only 3 modules -- | |
| ``_sre``, ``posix``, and ``strop``. | |
| * The ``configure`` script builds ``setup.cfg`` from ``setup.cfg.in``. This | |
| is needed for two reasons: to make building in subdirectories | |
| work, and to get the configured installation prefix. | |
| * Adds ``setup.py`` to the top directory of the source tree. ``setup.py`` | |
| is the largest piece of the puzzle, though not the most | |
| complicated. ``setup.py`` contains a subclass of the ``BuildExt`` | |
| class, and extends it with a ``detect_modules()`` method that does | |
| the work of figuring out when modules can be compiled, and adding | |
| them to the 'exts' list. | |
| Unresolved Issues | |
| ================= | |
| Do we need to make it possible to disable the 3 hard-wired modules | |
| without manually hacking the Makefiles? [Answer: No.] | |
| The Distutils always compile modules as shared libraries. How do | |
| we support compiling them statically into the resulting Python | |
| binary? | |
| [Answer: building a Python binary with the Distutils should be | |
| feasible, though no one has implemented it yet. This should be | |
| done someday, but isn't a pressing priority as messing around with | |
| the top-level ``Makefile.pre.in`` is good enough.] | |
| Copyright | |
| ========= | |
| This document has been placed in the public domain. | |
| .. | |
| Local Variables: | |
| mode: indented-text | |
| indent-tabs-mode: nil | |
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