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  <section id="python-r1-multi-impl-packages">
<h1>python-r1 — multi-impl packages<a class="headerlink" href="#python-r1-multi-impl-packages" title="Link to this heading">¶</a></h1>
<p>The <code class="docutils literal notranslate"><span class="pre">python-r1</span></code> eclass is used to install multi-impl packages.
It is considered an expert eclass — when possible, you should prefer
using <code class="docutils literal notranslate"><span class="pre">python-single-r1</span></code> instead.  For packages using distutils
or a similar Python build system, <code class="docutils literal notranslate"><span class="pre">distutils-r1</span></code> eclass should be used
instead.</p>
<p>Eclass reference: <a class="reference external" href="https://devmanual.gentoo.org/eclass-reference/python-r1.eclass/index.html">python-r1.eclass(5)</a></p>
<section id="manual-install">
<span id="index-0"></span><h2>Manual install<a class="headerlink" href="#manual-install" title="Link to this heading">¶</a></h2>
<p>The simplest case of multi-impl package is a package without a specific
build system.  The modules need to be installed manually here,
and <code class="docutils literal notranslate"><span class="pre">python_foreach_impl</span></code> function is used to repeat the install step
for all enabled implementations.</p>
<p>For simple use cases, the install command can be inlined:</p>
<div class="highlight-bash notranslate"><div class="highlight"><pre><span></span><span class="w"> </span><span class="c1"># Copyright 1999-2020 Gentoo Foundation</span>
<span class="w"> </span><span class="c1"># Distributed under the terms of the GNU General Public License v2</span>

<span class="w"> </span><span class="nv">EAPI</span><span class="o">=</span><span class="m">7</span>

<span class="hll"><span class="w"> </span><span class="nv">PYTHON_COMPAT</span><span class="o">=(</span><span class="w"> </span>python2_7<span class="w"> </span><span class="o">)</span>
</span><span class="hll"><span class="w"> </span>inherit<span class="w"> </span>python-r1
</span>
<span class="w"> </span><span class="nv">DESCRIPTION</span><span class="o">=</span><span class="s2">&quot;MySQL abstraction layer for python&quot;</span>
<span class="w"> </span><span class="nv">HOMEPAGE</span><span class="o">=</span><span class="s2">&quot;http://software.fionet.com/pSQL/&quot;</span>
<span class="w"> </span><span class="nv">SRC_URI</span><span class="o">=</span><span class="s2">&quot;http://software.fionet.com/pSQL/release/</span><span class="si">${</span><span class="nv">P</span><span class="si">}</span><span class="s2">.tar.gz&quot;</span>

<span class="w"> </span><span class="nv">SLOT</span><span class="o">=</span><span class="s2">&quot;0&quot;</span>
<span class="w"> </span><span class="nv">LICENSE</span><span class="o">=</span><span class="s2">&quot;GPL-2&quot;</span>
<span class="w"> </span><span class="nv">KEYWORDS</span><span class="o">=</span><span class="s2">&quot;~amd64 ~x86&quot;</span>
<span class="w"> </span><span class="nv">IUSE</span><span class="o">=</span><span class="s2">&quot;&quot;</span>
<span class="hll"><span class="w"> </span><span class="nv">REQUIRED_USE</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_REQUIRED_USE</span><span class="si">}</span><span class="s2">&quot;</span>
</span>
<span class="hll"><span class="w"> </span><span class="nv">RDEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_DEPS</span><span class="si">}</span><span class="s2">&quot;</span>
</span><span class="w"> </span><span class="nv">DEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">RDEPEND</span><span class="si">}</span><span class="s2">&quot;</span>

<span class="w"> </span>src_install<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>python_domodule<span class="w"> </span>pSQL.py
</span><span class="w"> </span><span class="o">}</span>
</pre></div>
</div>
<p>While <code class="docutils literal notranslate"><span class="pre">python_foreach_impl</span></code> can be repeated multiple times, it is
generally better to declare a function when multiple install commands
need to be executed:</p>
<div class="highlight-bash notranslate"><div class="highlight"><pre><span></span><span class="w"> </span><span class="c1"># Copyright 1999-2020 Gentoo Authors</span>
<span class="w"> </span><span class="c1"># Distributed under the terms of the GNU General Public License v2</span>

<span class="w"> </span><span class="nv">EAPI</span><span class="o">=</span><span class="m">7</span>

<span class="w"> </span><span class="nv">PYTHON_COMPAT</span><span class="o">=(</span><span class="w"> </span>python2_7<span class="w"> </span><span class="o">)</span>
<span class="w"> </span>inherit<span class="w"> </span>python-r1

<span class="w"> </span><span class="nv">DESCRIPTION</span><span class="o">=</span><span class="s2">&quot;Proxy cache for Gentoo packages&quot;</span>
<span class="w"> </span><span class="nv">HOMEPAGE</span><span class="o">=</span><span class="s2">&quot;https://sourceforge.net/projects/http-replicator&quot;</span>
<span class="w"> </span><span class="nv">SRC_URI</span><span class="o">=</span><span class="s2">&quot;mirror://sourceforge/</span><span class="si">${</span><span class="nv">PN</span><span class="si">}</span><span class="s2">/</span><span class="si">${</span><span class="nv">P</span><span class="si">}</span><span class="s2">.tgz&quot;</span>

<span class="w"> </span><span class="nv">LICENSE</span><span class="o">=</span><span class="s2">&quot;GPL-2&quot;</span>
<span class="w"> </span><span class="nv">SLOT</span><span class="o">=</span><span class="s2">&quot;0&quot;</span>
<span class="w"> </span><span class="nv">KEYWORDS</span><span class="o">=</span><span class="s2">&quot;~alpha amd64 hppa ppc ~sparc x86&quot;</span>
<span class="w"> </span><span class="nv">IUSE</span><span class="o">=</span><span class="s2">&quot;&quot;</span>
<span class="w"> </span><span class="nv">REQUIRED_USE</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_REQUIRED_USE</span><span class="si">}</span><span class="s2">&quot;</span>

<span class="w"> </span><span class="nv">RDEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_DEPS</span><span class="si">}</span><span class="s2">&quot;</span>
<span class="w"> </span><span class="nv">DEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">RDEPEND</span><span class="si">}</span><span class="s2">&quot;</span>

<span class="hll"><span class="w"> </span>python_install<span class="o">()</span><span class="w"> </span><span class="o">{</span>
</span><span class="hll"><span class="w">     </span>python_doscript<span class="w"> </span>http-replicator
</span><span class="hll"><span class="w">     </span>python_domodule<span class="w"> </span>*.py
</span><span class="hll"><span class="w"> </span><span class="o">}</span>
</span>
<span class="w"> </span>src_install<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>python_install
</span><span class="w"> </span><span class="o">}</span>
</pre></div>
</div>
</section>
<section id="dependencies">
<span id="index-1"></span><h2>Dependencies<a class="headerlink" href="#dependencies" title="Link to this heading">¶</a></h2>
<p>When depending on other Python packages, USE dependencies need to be
declared in order to ensure that the dependencies would be built against
all the Python implementations enabled for the package.  This is easily
done via appending the USE dependency string from <code class="docutils literal notranslate"><span class="pre">${PYTHON_USEDEP}</span></code>
to the dependencies:</p>
<div class="highlight-bash notranslate"><div class="highlight"><pre><span></span><span class="nv">RDEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_DEPS</span><span class="si">}</span>
<span class="s2">    sys-apps/portage[</span><span class="si">${</span><span class="nv">PYTHON_USEDEP</span><span class="si">}</span><span class="s2">]</span>
<span class="s2">&quot;</span>
<span class="nv">DEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">RDEPEND</span><span class="si">}</span><span class="s2">&quot;</span>
</pre></div>
</div>
</section>
<section id="pure-python-autotools-package">
<span id="index-2"></span><h2>Pure Python autotools package<a class="headerlink" href="#pure-python-autotools-package" title="Link to this heading">¶</a></h2>
<p>Another typical case for this eclass is to handle a pure Python package
with a non-standard build system.  In this case, it is generally
necessary to call phase functions via <code class="docutils literal notranslate"><span class="pre">python_foreach_impl</span></code>.  Whenever
possible, out-of-source builds are recommended (i.e. installing to
separate directories from a single source directory).</p>
<div class="highlight-bash notranslate"><div class="highlight"><pre><span></span><span class="w"> </span><span class="c1"># Copyright 1999-2020 Gentoo Authors</span>
<span class="w"> </span><span class="c1"># Distributed under the terms of the GNU General Public License v2</span>

<span class="w"> </span><span class="nv">EAPI</span><span class="o">=</span><span class="s2">&quot;6&quot;</span>
<span class="w"> </span><span class="nv">PYTHON_COMPAT</span><span class="o">=(</span><span class="w"> </span>python3_6<span class="w"> </span><span class="o">)</span>

<span class="w"> </span>inherit<span class="w"> </span>autotools<span class="w"> </span>python-r1

<span class="w"> </span><span class="nv">DESCRIPTION</span><span class="o">=</span><span class="s2">&quot;Python wrapper for libcangjie&quot;</span>
<span class="w"> </span><span class="nv">HOMEPAGE</span><span class="o">=</span><span class="s2">&quot;http://cangjians.github.io/&quot;</span>
<span class="w"> </span><span class="nv">SRC_URI</span><span class="o">=</span><span class="s2">&quot;https://github.com/Cangjians/py</span><span class="si">${</span><span class="nv">PN</span><span class="si">}</span><span class="s2">/releases/download/v</span><span class="si">${</span><span class="nv">PV</span><span class="si">}</span><span class="s2">/</span><span class="si">${</span><span class="nv">P</span><span class="p">#py</span><span class="si">}</span><span class="s2">.tar.xz&quot;</span>

<span class="w"> </span><span class="nv">LICENSE</span><span class="o">=</span><span class="s2">&quot;LGPL-3+&quot;</span>
<span class="w"> </span><span class="nv">SLOT</span><span class="o">=</span><span class="s2">&quot;0&quot;</span>
<span class="w"> </span><span class="nv">KEYWORDS</span><span class="o">=</span><span class="s2">&quot;~amd64 ~x86&quot;</span>
<span class="w"> </span><span class="nv">IUSE</span><span class="o">=</span><span class="s2">&quot;&quot;</span>
<span class="w"> </span><span class="nv">REQUIRED_USE</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_REQUIRED_USE</span><span class="si">}</span><span class="s2">&quot;</span>

<span class="w"> </span><span class="nv">RDEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_DEPS</span><span class="si">}</span>
<span class="s2">     app-i18n/libcangjie&quot;</span>
<span class="w"> </span><span class="nv">DEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">RDEPEND</span><span class="si">}</span>
<span class="s2">     dev-python/cython[</span><span class="si">${</span><span class="nv">PYTHON_USEDEP</span><span class="si">}</span><span class="s2">]</span>
<span class="s2">     virtual/pkgconfig&quot;</span>

<span class="w"> </span>src_prepare<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="w">     </span>default
<span class="w">     </span>eautoreconf
<span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_configure<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="w">     </span><span class="nb">local</span><span class="w"> </span><span class="nv">ECONF_SOURCE</span><span class="o">=</span><span class="si">${</span><span class="nv">S</span><span class="si">}</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>run_in_build_dir<span class="w"> </span>default
</span><span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_compile<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>run_in_build_dir<span class="w"> </span>default
</span><span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_test<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>run_in_build_dir<span class="w"> </span>default
</span><span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_install<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>run_in_build_dir<span class="w"> </span>default
</span><span class="w">     </span>einstalldocs
<span class="w">     </span>find<span class="w"> </span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">D</span><span class="si">}</span><span class="s2">&quot;</span><span class="w"> </span>-name<span class="w"> </span><span class="s1">&#39;*.la&#39;</span><span class="w"> </span>-delete<span class="w"> </span><span class="o">||</span><span class="w"> </span>die
<span class="w"> </span><span class="o">}</span>
</pre></div>
</div>
<p>Note the use of <code class="docutils literal notranslate"><span class="pre">run_in_build_dir</span></code> helper from <code class="docutils literal notranslate"><span class="pre">multibuild</span></code> eclass
(direct inherit is unnecessary here, as it is considered implicit part
of <code class="docutils literal notranslate"><span class="pre">python-r1</span></code> API).  It changes the directory to <code class="docutils literal notranslate"><span class="pre">BUILD_DIR</span></code> (which
is set by <code class="docutils literal notranslate"><span class="pre">python_foreach_impl</span></code> to a unique directory for each
implementation) and runs the specified command there.  In this case,
the ebuild performs autotools out-of-source build in a dedicated
directory for every interpreter enabled.</p>
<p>Also note that the in-build-dir call to <code class="docutils literal notranslate"><span class="pre">default</span></code> does not install
documentation from source directory, hence the additional
<code class="docutils literal notranslate"><span class="pre">einstalldocs</span></code> call.  Libtool-based packages install <code class="docutils literal notranslate"><span class="pre">.la</span></code> files
that are unnecessary for Python extensions, hence they are removed
afterwards.</p>
<p>If the package in question does not support out-of-source builds
(e.g. due to a buggy build system), <code class="docutils literal notranslate"><span class="pre">python_copy_sources</span></code> function
can be used to duplicate the package’s sources in build directories
for each implementation.  The same ebuild easily can be changed
to do that:</p>
<div class="highlight-bash notranslate"><div class="highlight"><pre><span></span><span class="w"> </span><span class="c1"># Copyright 1999-2020 Gentoo Authors</span>
<span class="w"> </span><span class="c1"># Distributed under the terms of the GNU General Public License v2</span>

<span class="w"> </span><span class="nv">EAPI</span><span class="o">=</span><span class="s2">&quot;6&quot;</span>
<span class="w"> </span><span class="nv">PYTHON_COMPAT</span><span class="o">=(</span><span class="w"> </span>python3_6<span class="w"> </span><span class="o">)</span>

<span class="w"> </span>inherit<span class="w"> </span>autotools<span class="w"> </span>python-r1

<span class="w"> </span><span class="nv">DESCRIPTION</span><span class="o">=</span><span class="s2">&quot;Python wrapper for libcangjie&quot;</span>
<span class="w"> </span><span class="nv">HOMEPAGE</span><span class="o">=</span><span class="s2">&quot;http://cangjians.github.io/&quot;</span>
<span class="w"> </span><span class="nv">SRC_URI</span><span class="o">=</span><span class="s2">&quot;https://github.com/Cangjians/py</span><span class="si">${</span><span class="nv">PN</span><span class="si">}</span><span class="s2">/releases/download/v</span><span class="si">${</span><span class="nv">PV</span><span class="si">}</span><span class="s2">/</span><span class="si">${</span><span class="nv">P</span><span class="p">#py</span><span class="si">}</span><span class="s2">.tar.xz&quot;</span>

<span class="w"> </span><span class="nv">LICENSE</span><span class="o">=</span><span class="s2">&quot;LGPL-3+&quot;</span>
<span class="w"> </span><span class="nv">SLOT</span><span class="o">=</span><span class="s2">&quot;0&quot;</span>
<span class="w"> </span><span class="nv">KEYWORDS</span><span class="o">=</span><span class="s2">&quot;~amd64 ~x86&quot;</span>
<span class="w"> </span><span class="nv">IUSE</span><span class="o">=</span><span class="s2">&quot;&quot;</span>
<span class="w"> </span><span class="nv">REQUIRED_USE</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_REQUIRED_USE</span><span class="si">}</span><span class="s2">&quot;</span>

<span class="w"> </span><span class="nv">RDEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_DEPS</span><span class="si">}</span>
<span class="s2">     app-i18n/libcangjie&quot;</span>
<span class="w"> </span><span class="nv">DEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">RDEPEND</span><span class="si">}</span>
<span class="s2">     dev-python/cython[</span><span class="si">${</span><span class="nv">PYTHON_USEDEP</span><span class="si">}</span><span class="s2">]</span>
<span class="s2">     virtual/pkgconfig&quot;</span>

<span class="w"> </span>src_prepare<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="w">     </span>default
<span class="w">     </span>eautoreconf
<span class="hll"><span class="w">     </span>python_copy_sources
</span><span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_configure<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>run_in_build_dir<span class="w"> </span>default
</span><span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_compile<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>run_in_build_dir<span class="w"> </span>default
</span><span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_test<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>run_in_build_dir<span class="w"> </span>default
</span><span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_install<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="w">     </span>python_foreach_impl<span class="w"> </span>run_in_build_dir<span class="w"> </span>default
</span><span class="w">     </span>einstalldocs
<span class="w">     </span>find<span class="w"> </span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">D</span><span class="si">}</span><span class="s2">&quot;</span><span class="w"> </span>-name<span class="w"> </span><span class="s1">&#39;*.la&#39;</span><span class="w"> </span>-delete<span class="w"> </span><span class="o">||</span><span class="w"> </span>die
<span class="w"> </span><span class="o">}</span>
</pre></div>
</div>
<p>Note that besides adding <code class="docutils literal notranslate"><span class="pre">python_copy_sources</span></code> call, <code class="docutils literal notranslate"><span class="pre">ECONF_SOURCE</span></code>
has been removed in order to disable out-of-source builds.</p>
</section>
<section id="conditional-python-use">
<h2>Conditional Python use<a class="headerlink" href="#conditional-python-use" title="Link to this heading">¶</a></h2>
<p>When the package installs Python components conditionally to a USE flag,
the respective USE conditional needs to be consistently used in metadata
variables and in <code class="docutils literal notranslate"><span class="pre">python_foreach_impl</span></code> calls.</p>
<div class="highlight-bash notranslate"><div class="highlight"><pre><span></span><span class="w"> </span><span class="c1"># Copyright 1999-2020 Gentoo Authors</span>
<span class="w"> </span><span class="c1"># Distributed under the terms of the GNU General Public License v2</span>

<span class="w"> </span><span class="nv">EAPI</span><span class="o">=</span><span class="m">6</span>
<span class="w"> </span><span class="nv">PYTHON_COMPAT</span><span class="o">=(</span><span class="w"> </span>python2_7<span class="w"> </span><span class="o">)</span>

<span class="w"> </span>inherit<span class="w"> </span>gnome2<span class="w"> </span>python-r1

<span class="w"> </span><span class="nv">DESCRIPTION</span><span class="o">=</span><span class="s2">&quot;Canvas widget for GTK+ using the cairo 2D library for drawing&quot;</span>
<span class="w"> </span><span class="nv">HOMEPAGE</span><span class="o">=</span><span class="s2">&quot;https://wiki.gnome.org/GooCanvas&quot;</span>

<span class="w"> </span><span class="nv">LICENSE</span><span class="o">=</span><span class="s2">&quot;LGPL-2&quot;</span>
<span class="w"> </span><span class="nv">SLOT</span><span class="o">=</span><span class="s2">&quot;2.0&quot;</span>
<span class="w"> </span><span class="nv">KEYWORDS</span><span class="o">=</span><span class="s2">&quot;~alpha amd64 ia64 ppc ppc64 sparc x86&quot;</span>
<span class="hll"><span class="w"> </span><span class="nv">IUSE</span><span class="o">=</span><span class="s2">&quot;python&quot;</span>
</span><span class="hll"><span class="w"> </span><span class="nv">REQUIRED_USE</span><span class="o">=</span><span class="s2">&quot;python? ( </span><span class="si">${</span><span class="nv">PYTHON_REQUIRED_USE</span><span class="si">}</span><span class="s2"> )&quot;</span>
</span>
<span class="w"> </span><span class="c1"># python only enables python specific binding override</span>
<span class="w"> </span><span class="nv">RDEPEND</span><span class="o">=</span><span class="s2">&quot;</span>
<span class="hll"><span class="s2">     python? (</span>
</span><span class="hll"><span class="s2">         </span><span class="si">${</span><span class="nv">PYTHON_DEPS</span><span class="si">}</span>
</span><span class="hll"><span class="s2">         &gt;=dev-python/pygobject-2.90.4:3[</span><span class="si">${</span><span class="nv">PYTHON_USEDEP</span><span class="si">}</span><span class="s2">] )</span>
</span><span class="s2"> &quot;</span>
<span class="w"> </span><span class="nv">DEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">RDEPEND</span><span class="si">}</span><span class="s2">&quot;</span>

<span class="w"> </span>src_prepare<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="w">     </span><span class="c1"># Python bindings are built/installed manually.</span>
<span class="w">     </span>sed<span class="w"> </span>-e<span class="w"> </span><span class="s2">&quot;/SUBDIRS = python/d&quot;</span><span class="w"> </span>-i<span class="w"> </span>bindings/Makefile.am<span class="w"> </span><span class="se">\</span>
<span class="w">         </span>bindings/Makefile.in<span class="w"> </span><span class="o">||</span><span class="w"> </span>die

<span class="w">     </span>gnome2_src_prepare
<span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_configure<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="w">     </span>gnome2_src_configure<span class="w"> </span><span class="se">\</span>
<span class="w">         </span>--disable-python
<span class="w"> </span><span class="o">}</span>

<span class="w"> </span>src_install<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="w">     </span>gnome2_src_install

<span class="hll"><span class="w">     </span><span class="k">if</span><span class="w"> </span>use<span class="w"> </span>python<span class="p">;</span><span class="w"> </span><span class="k">then</span>
</span><span class="hll"><span class="w">         </span>sub_install<span class="o">()</span><span class="w"> </span><span class="o">{</span>
</span><span class="hll"><span class="w">             </span>python_moduleinto<span class="w"> </span><span class="k">$(</span>python<span class="w"> </span>-c<span class="w"> </span><span class="s2">&quot;import gi;print gi._overridesdir&quot;</span><span class="k">)</span>
</span><span class="hll"><span class="w">             </span>python_domodule<span class="w"> </span>bindings/python/GooCanvas.py
</span><span class="hll"><span class="w">         </span><span class="o">}</span>
</span><span class="hll"><span class="w">         </span>python_foreach_impl<span class="w"> </span>sub_install
</span><span class="hll"><span class="w">     </span><span class="k">fi</span>
</span><span class="w"> </span><span class="o">}</span>
</pre></div>
</div>
<p>Note that in many cases, you will end up having to disable upstream
rules for installing Python files as they are suitable only for
single-impl installs.</p>
</section>
<section id="additional-build-time-python-use">
<span id="index-3"></span><h2>Additional build-time Python use<a class="headerlink" href="#additional-build-time-python-use" title="Link to this heading">¶</a></h2>
<p>Some packages additionally require Python at build time, independently
of Python components installed (i.e. outside <code class="docutils literal notranslate"><span class="pre">python_foreach_impl</span></code>).
The eclass provides extensive API for this purpose but for now we’ll
focus on the simplest case where the global code does not have any
dependencies or they are a subset of dependencies declared already.</p>
<p>In this case, it is sufficient to call <code class="docutils literal notranslate"><span class="pre">python_setup</span></code> before
the routine requiring Python.  It will choose the most preferred
of enabled implementations, and set the global environment for it.  Note
that it is entirely normal that the same environment will be set inside
<code class="docutils literal notranslate"><span class="pre">python_foreach_impl</span></code> afterwards.</p>
<div class="highlight-bash notranslate"><div class="highlight"><pre><span></span><span class="linenos"> 1</span><span class="w"> </span><span class="c1"># Copyright 1999-2020 Gentoo Authors</span>
<span class="linenos"> 2</span><span class="w"> </span><span class="c1"># Distributed under the terms of the GNU General Public License v2</span>
<span class="linenos"> 3</span>
<span class="linenos"> 4</span><span class="w"> </span><span class="nv">EAPI</span><span class="o">=</span><span class="s2">&quot;7&quot;</span>
<span class="linenos"> 5</span>
<span class="linenos"> 6</span><span class="w"> </span><span class="nv">PYTHON_COMPAT</span><span class="o">=(</span><span class="w"> </span>python<span class="o">{</span>3_6,3_7<span class="o">}</span><span class="w"> </span><span class="o">)</span>
<span class="linenos"> 7</span><span class="w"> </span><span class="nv">PYTHON_REQ_USE</span><span class="o">=</span><span class="s2">&quot;ncurses,readline&quot;</span>
<span class="linenos"> 8</span><span class="w"> </span>inherit<span class="w"> </span>python-r1
<span class="linenos"> 9</span>
<span class="linenos">10</span><span class="w"> </span><span class="nv">DESCRIPTION</span><span class="o">=</span><span class="s2">&quot;QEMU + Kernel-based Virtual Machine userland tools&quot;</span>
<span class="linenos">11</span><span class="w"> </span><span class="nv">HOMEPAGE</span><span class="o">=</span><span class="s2">&quot;http://www.qemu.org http://www.linux-kvm.org&quot;</span>
<span class="linenos">12</span><span class="w"> </span><span class="nv">SRC_URI</span><span class="o">=</span><span class="s2">&quot;http://wiki.qemu-project.org/download/</span><span class="si">${</span><span class="nv">P</span><span class="si">}</span><span class="s2">.tar.xz&quot;</span>
<span class="linenos">13</span>
<span class="linenos">14</span><span class="w"> </span><span class="nv">LICENSE</span><span class="o">=</span><span class="s2">&quot;GPL-2 LGPL-2 BSD-2&quot;</span>
<span class="linenos">15</span><span class="w"> </span><span class="nv">SLOT</span><span class="o">=</span><span class="s2">&quot;0&quot;</span>
<span class="linenos">16</span><span class="w"> </span><span class="nv">KEYWORDS</span><span class="o">=</span><span class="s2">&quot;amd64 ~arm64 ~ppc ~ppc64 x86&quot;</span>
<span class="hll"><span class="linenos">17</span><span class="w"> </span><span class="nv">IUSE</span><span class="o">=</span><span class="s2">&quot;python&quot;</span>
</span><span class="hll"><span class="linenos">18</span><span class="w"> </span><span class="nv">REQUIRED_USE</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_REQUIRED_USE</span><span class="si">}</span><span class="s2">&quot;</span>
</span><span class="linenos">19</span>
<span class="hll"><span class="linenos">20</span><span class="w"> </span><span class="nv">BDEPEND</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">PYTHON_DEPS</span><span class="si">}</span><span class="s2">&quot;</span>
</span><span class="hll"><span class="linenos">21</span><span class="w"> </span><span class="nv">RDEPEND</span><span class="o">=</span><span class="s2">&quot;python? ( </span><span class="si">${</span><span class="nv">PYTHON_DEPS</span><span class="si">}</span><span class="s2"> )&quot;</span>
</span><span class="linenos">22</span>
<span class="linenos">23</span><span class="w"> </span>src_configure<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="hll"><span class="linenos">24</span><span class="w">     </span>python_setup
</span><span class="linenos">25</span><span class="w">     </span>./configure<span class="w"> </span><span class="o">||</span><span class="w"> </span>die
<span class="linenos">26</span><span class="w"> </span><span class="o">}</span>
<span class="linenos">27</span>
<span class="hll"><span class="linenos">28</span><span class="w"> </span>qemu_python_install<span class="o">()</span><span class="w"> </span><span class="o">{</span>
</span><span class="hll"><span class="linenos">29</span><span class="w">     </span>python_domodule<span class="w"> </span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">S</span><span class="si">}</span><span class="s2">/python/qemu&quot;</span>
</span><span class="hll"><span class="linenos">30</span>
</span><span class="hll"><span class="linenos">31</span><span class="w">     </span>python_doscript<span class="w"> </span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">S</span><span class="si">}</span><span class="s2">/scripts/kvm/vmxcap&quot;</span>
</span><span class="hll"><span class="linenos">32</span><span class="w">     </span>python_doscript<span class="w"> </span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">S</span><span class="si">}</span><span class="s2">/scripts/qmp/qmp-shell&quot;</span>
</span><span class="hll"><span class="linenos">33</span><span class="w">     </span>python_doscript<span class="w"> </span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">S</span><span class="si">}</span><span class="s2">/scripts/qmp/qemu-ga-client&quot;</span>
</span><span class="hll"><span class="linenos">34</span><span class="w"> </span><span class="o">}</span>
</span><span class="linenos">35</span>
<span class="linenos">36</span><span class="w"> </span>src_install<span class="o">()</span><span class="w"> </span><span class="o">{</span>
<span class="linenos">37</span><span class="w">     </span>default
<span class="hll"><span class="linenos">38</span><span class="w">     </span><span class="k">if</span><span class="w"> </span>use<span class="w"> </span>python<span class="p">;</span><span class="w"> </span><span class="k">then</span>
</span><span class="hll"><span class="linenos">39</span><span class="w">         </span>python_foreach_impl<span class="w"> </span>qemu_python_install
</span><span class="hll"><span class="linenos">40</span><span class="w">     </span><span class="k">fi</span>
</span><span class="linenos">41</span><span class="w"> </span><span class="o">}</span>
</pre></div>
</div>
<p>Note that the parts affecting installation of runtime components
(<code class="docutils literal notranslate"><span class="pre">RDEPEND</span></code>, <code class="docutils literal notranslate"><span class="pre">python_foreach_impl</span></code>) are made conditional to the USE
flag, while parts affecting build time (<code class="docutils literal notranslate"><span class="pre">REQUIRED_USE</span></code>, <code class="docutils literal notranslate"><span class="pre">BDEPEND</span></code>,
<code class="docutils literal notranslate"><span class="pre">python_setup</span></code>) are unconditional.</p>
</section>
</section>


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