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id="colour-scheme-cycler" onClick="setColourScheme(nextColourScheme())"> <svg aria-hidden="true" class="colour-scheme-icon-when-auto"><use href="#svg-sun-half"></use></svg> <svg aria-hidden="true" class="colour-scheme-icon-when-dark"><use href="#svg-moon"></use></svg> <svg aria-hidden="true" class="colour-scheme-icon-when-light"><use href="#svg-sun"></use></svg> <span class="visually-hidden">Toggle light / dark / auto colour theme</span> </button> </header> <article> <section id="pep-content"> <h1 class="page-title">PEP 3149 – ABI version tagged .so files</h1> <dl class="rfc2822 field-list simple"> <dt class="field-odd">Author<span class="colon">:</span></dt> <dd class="field-odd">Barry Warsaw <barry at python.org></dd> <dt class="field-even">Status<span class="colon">:</span></dt> <dd class="field-even"><abbr title="Accepted and implementation complete, or no longer active">Final</abbr></dd> <dt class="field-odd">Type<span class="colon">:</span></dt> <dd class="field-odd"><abbr title="Normative PEP with a new feature for Python, implementation change for CPython or interoperability standard for the ecosystem">Standards Track</abbr></dd> <dt class="field-even">Created<span class="colon">:</span></dt> <dd class="field-even">09-Jul-2010</dd> <dt class="field-odd">Python-Version<span class="colon">:</span></dt> <dd class="field-odd">3.2</dd> <dt class="field-even">Post-History<span class="colon">:</span></dt> <dd class="field-even">14-Jul-2010, 22-Jul-2010</dd> <dt class="field-odd">Resolution<span class="colon">:</span></dt> <dd class="field-odd"><a class="reference external" href="https://mail.python.org/pipermail/python-dev/2010-September/103408.html">Python-Dev message</a></dd> </dl> <hr class="docutils" /> <section id="contents"> <details><summary>Table of Contents</summary><ul class="simple"> <li><a class="reference internal" href="#abstract">Abstract</a></li> <li><a class="reference internal" href="#background">Background</a></li> <li><a class="reference internal" href="#rationale">Rationale</a></li> <li><a class="reference internal" href="#proposal">Proposal</a></li> <li><a class="reference internal" href="#proven-approach">Proven approach</a></li> <li><a class="reference internal" href="#windows">Windows</a></li> <li><a class="reference internal" href="#pep-384">PEP 384</a></li> <li><a class="reference internal" href="#alternatives">Alternatives</a><ul> <li><a class="reference internal" href="#independent-directories-or-symlinks">Independent directories or symlinks</a></li> <li><a class="reference internal" href="#don-t-share-packages-with-extension-modules">Don’t share packages with extension modules</a></li> </ul> </li> <li><a class="reference internal" href="#reference-implementation">Reference implementation</a></li> <li><a class="reference internal" href="#references">References</a></li> <li><a class="reference internal" href="#copyright">Copyright</a></li> </ul> </details></section> <section id="abstract"> <h2><a class="toc-backref" href="#abstract" role="doc-backlink">Abstract</a></h2> <p><a class="pep reference internal" href="../pep-3147/" title="PEP 3147 – PYC Repository Directories">PEP 3147</a> described an extension to Python’s import machinery that improved the sharing of Python source code, by allowing more than one byte compilation file (.pyc) to be co-located with each source file.</p> <p>This PEP defines an adjunct feature which allows the co-location of extension module files (.so) in a similar manner. This optional, build-time feature will enable downstream distributions of Python to more easily provide more than one Python major version at a time.</p> </section> <section id="background"> <h2><a class="toc-backref" href="#background" role="doc-backlink">Background</a></h2> <p><a class="pep reference internal" href="../pep-3147/" title="PEP 3147 – PYC Repository Directories">PEP 3147</a> defined the file system layout for a pure-Python package, where multiple versions of Python are available on the system. For example, where the <code class="docutils literal notranslate"><span class="pre">alpha</span></code> package containing source modules <code class="docutils literal notranslate"><span class="pre">one.py</span></code> and <code class="docutils literal notranslate"><span class="pre">two.py</span></code> exist on a system with Python 3.2 and 3.3, the post-byte compilation file system layout would be:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">alpha</span><span class="o">/</span> <span class="n">__pycache__</span><span class="o">/</span> <span class="fm">__init__</span><span class="o">.</span><span class="n">cpython</span><span class="o">-</span><span class="mf">32.</span><span class="n">pyc</span> <span class="fm">__init__</span><span class="o">.</span><span class="n">cpython</span><span class="o">-</span><span class="mf">33.</span><span class="n">pyc</span> <span class="n">one</span><span class="o">.</span><span class="n">cpython</span><span class="o">-</span><span class="mf">32.</span><span class="n">pyc</span> <span class="n">one</span><span class="o">.</span><span class="n">cpython</span><span class="o">-</span><span class="mf">33.</span><span class="n">pyc</span> <span class="n">two</span><span class="o">.</span><span class="n">cpython</span><span class="o">-</span><span class="mf">32.</span><span class="n">pyc</span> <span class="n">two</span><span class="o">.</span><span class="n">cpython</span><span class="o">-</span><span class="mf">33.</span><span class="n">pyc</span> <span class="fm">__init__</span><span class="o">.</span><span class="n">py</span> <span class="n">one</span><span class="o">.</span><span class="n">py</span> <span class="n">two</span><span class="o">.</span><span class="n">py</span> </pre></div> </div> <p>For packages with extension modules, a similar differentiation is needed for the module’s .so files. Extension modules compiled for different Python major versions are incompatible with each other due to changes in the ABI. Different configuration/compilation options for the same Python version can result in different ABIs (e.g. –with-wide-unicode).</p> <p>While <a class="pep reference internal" href="../pep-0384/" title="PEP 384 – Defining a Stable ABI">PEP 384</a> defines a stable ABI, it will minimize, but not eliminate extension module incompatibilities between Python builds or major versions. Thus a mechanism for discriminating extension module file names is proposed.</p> </section> <section id="rationale"> <h2><a class="toc-backref" href="#rationale" role="doc-backlink">Rationale</a></h2> <p>Linux distributions such as Ubuntu <a class="footnote-reference brackets" href="#id9" id="id1">[3]</a> and Debian <a class="footnote-reference brackets" href="#id10" id="id2">[4]</a> provide more than one Python version at the same time to their users. For example, Ubuntu 9.10 Karmic Koala users can install Python 2.5, 2.6, and 3.1, with Python 2.6 being the default.</p> <p>In order to share as much as possible between the available Python versions, these distributions install third party package modules (<code class="docutils literal notranslate"><span class="pre">.pyc</span></code> and <code class="docutils literal notranslate"><span class="pre">.so</span></code> files) into <code class="docutils literal notranslate"><span class="pre">/usr/share/pyshared</span></code> and symlink to them from <code class="docutils literal notranslate"><span class="pre">/usr/lib/pythonX.Y/dist-packages</span></code>. The symlinks exist because in a pre-<a class="pep reference internal" href="../pep-3147/" title="PEP 3147 – PYC Repository Directories">PEP 3147</a> world (i.e < Python 3.2), the <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> files resulting from byte compilation by the various installed Pythons will name collide with each other. For Python versions >= 3.2, all pure-Python packages can be shared, because the <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> files will no longer cause file system naming conflicts. Eliminating these symlinks makes for a simpler, more robust Python distribution.</p> <p>A similar situation arises with shared library extensions. Because extension modules are typically named <code class="docutils literal notranslate"><span class="pre">foo.so</span></code> for a <code class="docutils literal notranslate"><span class="pre">foo</span></code> extension module, these would also name collide if <code class="docutils literal notranslate"><span class="pre">foo</span></code> was provided for more than one Python version.</p> <p>In addition, because different configuration/compilation options for the same Python version can cause different ABIs to be presented to extension modules. On POSIX systems for example, the configure options <code class="docutils literal notranslate"><span class="pre">--with-pydebug</span></code>, <code class="docutils literal notranslate"><span class="pre">--with-pymalloc</span></code>, and <code class="docutils literal notranslate"><span class="pre">--with-wide-unicode</span></code> all change the ABI. This PEP proposes to encode build-time options in the file name of the <code class="docutils literal notranslate"><span class="pre">.so</span></code> extension module files.</p> <p>PyPy <a class="footnote-reference brackets" href="#id11" id="id3">[5]</a> can also benefit from this PEP, allowing it to avoid name collisions in extension modules built for its API, but with a different <code class="docutils literal notranslate"><span class="pre">.so</span></code> tag.</p> </section> <section id="proposal"> <h2><a class="toc-backref" href="#proposal" role="doc-backlink">Proposal</a></h2> <p>The configure/compilation options chosen at Python interpreter build-time will be encoded in the shared library file name for extension modules. This “tag” will appear between the module base name and the operation file system extension for shared libraries.</p> <p>The following information <em>MUST</em> be included in the shared library file name:</p> <ul class="simple"> <li>The Python implementation (e.g. cpython, pypy, jython, etc.)</li> <li>The interpreter’s major and minor version numbers</li> </ul> <p>These two fields are separated by a hyphen and no dots are to appear between the major and minor version numbers. E.g. <code class="docutils literal notranslate"><span class="pre">cpython-32</span></code>.</p> <p>Python implementations <em>MAY</em> include additional flags in the file name tag as appropriate. For example, on POSIX systems these flags will also contribute to the file name:</p> <ul class="simple"> <li><code class="docutils literal notranslate"><span class="pre">--with-pydebug</span></code> (flag: <code class="docutils literal notranslate"><span class="pre">d</span></code>)</li> <li><code class="docutils literal notranslate"><span class="pre">--with-pymalloc</span></code> (flag: <code class="docutils literal notranslate"><span class="pre">m</span></code>)</li> <li><code class="docutils literal notranslate"><span class="pre">--with-wide-unicode</span></code> (flag: <code class="docutils literal notranslate"><span class="pre">u</span></code>)</li> </ul> <p>By default in Python 3.2, <code class="docutils literal notranslate"><span class="pre">configure</span></code> enables <code class="docutils literal notranslate"><span class="pre">--with-pymalloc</span></code> so shared library file names would appear as <code class="docutils literal notranslate"><span class="pre">foo.cpython-32m.so</span></code>. When the other two flags are also enabled, the file names would be <code class="docutils literal notranslate"><span class="pre">foo.cpython-32dmu.so</span></code>.</p> <p>The shared library file name tag is used unconditionally; it cannot be changed. The tag and extension module suffix are available through the <code class="docutils literal notranslate"><span class="pre">sysconfig</span></code> modules via the following variables:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">sysconfig</span><span class="o">.</span><span class="n">get_config_var</span><span class="p">(</span><span class="s1">'EXT_SUFFIX'</span><span class="p">)</span> <span class="go">'.cpython-32mu.so'</span> <span class="gp">>>> </span><span class="n">sysconfig</span><span class="o">.</span><span class="n">get_config_var</span><span class="p">(</span><span class="s1">'SOABI'</span><span class="p">)</span> <span class="go">'cpython-32mu'</span> </pre></div> </div> <p>Note that <code class="docutils literal notranslate"><span class="pre">$SOABI</span></code> contains just the tag, while <code class="docutils literal notranslate"><span class="pre">$EXT_SUFFIX</span></code> includes the platform extension for shared library files, and is the exact suffix added to the extension module name.</p> <p>For an arbitrary package <code class="docutils literal notranslate"><span class="pre">foo</span></code>, you might see these files when the distribution package was installed:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python</span><span class="o">/</span><span class="n">foo</span><span class="o">.</span><span class="n">cpython</span><span class="o">-</span><span class="mi">32</span><span class="n">m</span><span class="o">.</span><span class="n">so</span> <span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python</span><span class="o">/</span><span class="n">foo</span><span class="o">.</span><span class="n">cpython</span><span class="o">-</span><span class="mi">33</span><span class="n">m</span><span class="o">.</span><span class="n">so</span> </pre></div> </div> <p>(These paths are for example purposes only. Distributions are free to use whatever filesystem layout they choose, and nothing in this PEP changes the locations where from-source builds of Python are installed.)</p> <p>Python’s dynamic module loader will recognize and import shared library extension modules with a tag that matches its build-time options. For backward compatibility, Python will also continue to import untagged extension modules, e.g. <code class="docutils literal notranslate"><span class="pre">foo.so</span></code>.</p> <p>This shared library tag would be used globally for all distutils-based extension modules, regardless of where on the file system they are built. Extension modules built by means other than distutils would either have to calculate the tag manually, or fallback to the non-tagged <code class="docutils literal notranslate"><span class="pre">.so</span></code> file name.</p> </section> <section id="proven-approach"> <h2><a class="toc-backref" href="#proven-approach" role="doc-backlink">Proven approach</a></h2> <p>The approach described here is already proven, in a sense, on Debian and Ubuntu system where different extensions are used for debug builds of Python and extension modules. Debug builds on Windows also already use a different file extension for dynamic libraries, and in fact encoded (in a different way than proposed in this PEP) the Python major and minor version in the <code class="docutils literal notranslate"><span class="pre">.dll</span></code> file name.</p> </section> <section id="windows"> <h2><a class="toc-backref" href="#windows" role="doc-backlink">Windows</a></h2> <p>This PEP only addresses build issues on POSIX systems that use the <code class="docutils literal notranslate"><span class="pre">configure</span></code> script. While Windows or other platform support is not explicitly disallowed under this PEP, platform expertise is needed in order to evaluate, describe, and implement support on such platforms. It is not currently clear that the facilities in this PEP are even useful for Windows.</p> </section> <section id="pep-384"> <h2><a class="toc-backref" href="#pep-384" role="doc-backlink">PEP 384</a></h2> <p><a class="pep reference internal" href="../pep-0384/" title="PEP 384 – Defining a Stable ABI">PEP 384</a> defines a stable ABI for extension modules. In theory, universal adoption of <a class="pep reference internal" href="../pep-0384/" title="PEP 384 – Defining a Stable ABI">PEP 384</a> would eliminate the need for this PEP because all extension modules could be compatible with any Python version. In practice of course, it will be impossible to achieve universal adoption, and as described above, different build-time flags still affect the ABI. Thus even with a stable ABI, this PEP may still be necessary. While a complete specification is reserved for <a class="pep reference internal" href="../pep-0384/" title="PEP 384 – Defining a Stable ABI">PEP 384</a>, here is a discussion of the relevant issues.</p> <p><a class="pep reference internal" href="../pep-0384/" title="PEP 384 – Defining a Stable ABI">PEP 384</a> describes a change to <code class="docutils literal notranslate"><span class="pre">PyModule_Create()</span></code> where <code class="docutils literal notranslate"><span class="pre">3</span></code> is passed as the API version if the extension was compiled with <code class="docutils literal notranslate"><span class="pre">Py_LIMITED_API</span></code>. This should be formalized into an official macro called <code class="docutils literal notranslate"><span class="pre">PYTHON_ABI_VERSION</span></code> to mirror <code class="docutils literal notranslate"><span class="pre">PYTHON_API_VERSION</span></code>. If and when the ABI changes in an incompatible way, this version number would be bumped. To facilitate sharing, Python would be extended to search for extension modules with the <code class="docutils literal notranslate"><span class="pre">PYTHON_ABI_VERSION</span></code> number in its name. The prefix <code class="docutils literal notranslate"><span class="pre">abi</span></code> is reserved for Python’s use.</p> <p>Thus, an initial implementation of <a class="pep reference internal" href="../pep-0384/" title="PEP 384 – Defining a Stable ABI">PEP 384</a>, when Python is configured with the default set of flags, would search for the following file names when extension module <code class="docutils literal notranslate"><span class="pre">foo</span></code> is imported (in this order):</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">foo</span><span class="o">.</span><span class="n">cpython</span><span class="o">-</span><span class="n">XYm</span><span class="o">.</span><span class="n">so</span> <span class="n">foo</span><span class="o">.</span><span class="n">abi3</span><span class="o">.</span><span class="n">so</span> <span class="n">foo</span><span class="o">.</span><span class="n">so</span> </pre></div> </div> <p>The distutils <a class="footnote-reference brackets" href="#id12" id="id4">[6]</a> <code class="docutils literal notranslate"><span class="pre">build_ext</span></code> command would also have to be extended to compile to shared library files with the <code class="docutils literal notranslate"><span class="pre">abi3</span></code> tag, when the module author indicates that their extension supports that version of the ABI. This could be done in a backward compatible way by adding a keyword argument to the <code class="docutils literal notranslate"><span class="pre">Extension</span></code> class, such as:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">Extension</span><span class="p">(</span><span class="s1">'foo'</span><span class="p">,</span> <span class="p">[</span><span class="s1">'foo.c'</span><span class="p">],</span> <span class="n">abi</span><span class="o">=</span><span class="mi">3</span><span class="p">)</span> </pre></div> </div> <p>Martin v. Löwis describes his thoughts <a class="footnote-reference brackets" href="#id13" id="id5">[7]</a> about the applicability of this PEP to <a class="pep reference internal" href="../pep-0384/" title="PEP 384 – Defining a Stable ABI">PEP 384</a>. In summary:</p> <ul class="simple"> <li><code class="docutils literal notranslate"><span class="pre">--with-pydebug</span></code> would not be supported by the stable ABI because this changes the layout of <code class="docutils literal notranslate"><span class="pre">PyObject</span></code>, which is an exposed structure.</li> <li><code class="docutils literal notranslate"><span class="pre">--with-pymalloc</span></code> has no bearing on the issue.</li> <li><code class="docutils literal notranslate"><span class="pre">--with-wide-unicode</span></code> is trickier, though Martin’s inclination is to force the stable ABI to use a <code class="docutils literal notranslate"><span class="pre">Py_UNICODE</span></code> that matches the platform’s <code class="docutils literal notranslate"><span class="pre">wchar_t</span></code>.</li> </ul> </section> <section id="alternatives"> <h2><a class="toc-backref" href="#alternatives" role="doc-backlink">Alternatives</a></h2> <p>In the initial python-dev thread <a class="footnote-reference brackets" href="#id14" id="id6">[8]</a> where this idea was first introduced, several alternatives were suggested. For completeness they are listed here, along with the reasons for not adopting them.</p> <section id="independent-directories-or-symlinks"> <h3><a class="toc-backref" href="#independent-directories-or-symlinks" role="doc-backlink">Independent directories or symlinks</a></h3> <p>Debian and Ubuntu could simply add a version-specific directory to <code class="docutils literal notranslate"><span class="pre">sys.path</span></code> that would contain just the extension modules for that version of Python. Or the symlink trick eliminated in <a class="pep reference internal" href="../pep-3147/" title="PEP 3147 – PYC Repository Directories">PEP 3147</a> could be retained for just shared libraries. This approach is rejected because it propagates the essential complexity that <a class="pep reference internal" href="../pep-3147/" title="PEP 3147 – PYC Repository Directories">PEP 3147</a> tries to avoid, and adds potentially several additional directories to search for all modules, even when the number of extension modules is much fewer than the total number of Python packages. For example, builds were made available both with and without wide unicode, with and without pydebug, and with and without pymalloc, the total number of directories search increases substantially.</p> </section> <section id="don-t-share-packages-with-extension-modules"> <h3><a class="toc-backref" href="#don-t-share-packages-with-extension-modules" role="doc-backlink">Don’t share packages with extension modules</a></h3> <p>It has been suggested that Python packages with extension modules not be shared among all supported Python versions on a distribution. Even with adoption of <a class="pep reference internal" href="../pep-3149/" title="PEP 3149 – ABI version tagged .so files">PEP 3149</a>, extension modules will have to be compiled for every supported Python version, so perhaps sharing of such packages isn’t useful anyway. Not sharing packages with extensions though is infeasible for several reasons.</p> <p>If a pure-Python package is shared in one version, should it suddenly be not-shared if the next release adds an extension module for speed? Also, even though all extension shared libraries will be compiled and distributed once for every supported Python, there’s a big difference between duplicating the <code class="docutils literal notranslate"><span class="pre">.so</span></code> files and duplicating all <code class="docutils literal notranslate"><span class="pre">.py</span></code> files. The extra size increases the download time for such packages, and more immediately, increases the space pressures on already constrained distribution CD-ROMs.</p> </section> </section> <section id="reference-implementation"> <h2><a class="toc-backref" href="#reference-implementation" role="doc-backlink">Reference implementation</a></h2> <p>Work on this code is tracked in a Bazaar branch on Launchpad <a class="footnote-reference brackets" href="#id15" id="id7">[9]</a> until it’s ready for merge into Python 3.2. The work-in-progress diff can also be viewed <a class="footnote-reference brackets" href="#id16" id="id8">[10]</a> and is updated automatically as new changes are uploaded.</p> </section> <section id="references"> <h2><a class="toc-backref" href="#references" role="doc-backlink">References</a></h2> <aside class="footnote-list brackets"> <aside class="footnote brackets" id="id9" role="doc-footnote"> <dt class="label" id="id9">[<a href="#id1">3</a>]</dt> <dd>Ubuntu: <<a class="reference external" href="http://www.ubuntu.com">http://www.ubuntu.com</a>></aside> <aside class="footnote brackets" id="id10" role="doc-footnote"> <dt class="label" id="id10">[<a href="#id2">4</a>]</dt> <dd>Debian: <<a class="reference external" href="http://www.debian.org">http://www.debian.org</a>></aside> <aside class="footnote brackets" id="id11" role="doc-footnote"> <dt class="label" id="id11">[<a href="#id3">5</a>]</dt> <dd><a class="reference external" href="http://codespeak.net/pypy/dist/pypy/doc/">http://codespeak.net/pypy/dist/pypy/doc/</a></aside> <aside class="footnote brackets" id="id12" role="doc-footnote"> <dt class="label" id="id12">[<a href="#id4">6</a>]</dt> <dd><a class="reference external" href="http://docs.python.org/py3k/distutils/index.html">http://docs.python.org/py3k/distutils/index.html</a></aside> <aside class="footnote brackets" id="id13" role="doc-footnote"> <dt class="label" id="id13">[<a href="#id5">7</a>]</dt> <dd><a class="reference external" href="https://mail.python.org/pipermail/python-dev/2010-August/103330.html">https://mail.python.org/pipermail/python-dev/2010-August/103330.html</a></aside> <aside class="footnote brackets" id="id14" role="doc-footnote"> <dt class="label" id="id14">[<a href="#id6">8</a>]</dt> <dd><a class="reference external" href="https://mail.python.org/pipermail/python-dev/2010-June/100998.html">https://mail.python.org/pipermail/python-dev/2010-June/100998.html</a></aside> <aside class="footnote brackets" id="id15" role="doc-footnote"> <dt class="label" id="id15">[<a href="#id7">9</a>]</dt> <dd><a class="reference external" href="https://code.edge.launchpad.net/~barry/python/sovers">https://code.edge.launchpad.net/~barry/python/sovers</a></aside> <aside class="footnote brackets" id="id16" role="doc-footnote"> <dt class="label" id="id16">[<a href="#id8">10</a>]</dt> <dd><a class="reference external" href="https://code.edge.launchpad.net/~barry/python/sovers/+merge/29411">https://code.edge.launchpad.net/~barry/python/sovers/+merge/29411</a></aside> </aside> </section> <section id="copyright"> <h2><a class="toc-backref" href="#copyright" role="doc-backlink">Copyright</a></h2> <p>This document has been placed in the public domain.</p> </section> </section> <hr class="docutils" /> <p>Source: <a class="reference external" href="https://github.com/python/peps/blob/main/peps/pep-3149.rst">https://github.com/python/peps/blob/main/peps/pep-3149.rst</a></p> <p>Last modified: <a class="reference external" href="https://github.com/python/peps/commits/main/peps/pep-3149.rst">2023-09-09 17:39:29 GMT</a></p> </article> <nav id="pep-sidebar"> <h2>Contents</h2> <ul> <li><a class="reference internal" href="#abstract">Abstract</a></li> <li><a class="reference internal" href="#background">Background</a></li> <li><a class="reference internal" href="#rationale">Rationale</a></li> <li><a class="reference internal" href="#proposal">Proposal</a></li> <li><a class="reference internal" href="#proven-approach">Proven approach</a></li> <li><a class="reference internal" href="#windows">Windows</a></li> <li><a class="reference internal" href="#pep-384">PEP 384</a></li> <li><a class="reference internal" href="#alternatives">Alternatives</a><ul> <li><a class="reference internal" href="#independent-directories-or-symlinks">Independent directories or symlinks</a></li> <li><a class="reference internal" href="#don-t-share-packages-with-extension-modules">Don’t share packages with extension modules</a></li> </ul> </li> <li><a class="reference internal" href="#reference-implementation">Reference implementation</a></li> <li><a class="reference internal" href="#references">References</a></li> <li><a class="reference internal" href="#copyright">Copyright</a></li> </ul> <br> <a id="source" href="https://github.com/python/peps/blob/main/peps/pep-3149.rst">Page Source (GitHub)</a> </nav> </section> <script src="../_static/colour_scheme.js"></script> <script src="../_static/wrap_tables.js"></script> <script src="../_static/sticky_banner.js"></script> </body> </html>