ef21e5ee60
There's no change in content except for amending the title of the section to mention "frameworks", as e.g. I don't consider Qt a language, and it's likely there will be more of similar cases in future. To be certain, I checked diff of the generated HTMLs.
447 lines
15 KiB
XML
447 lines
15 KiB
XML
<section xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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xml:id="sec-python">
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<title>Python</title>
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<para>
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Currently supported interpreters are <varname>python26</varname>, <varname>python27</varname>,
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<varname>python33</varname>, <varname>python34</varname>, <varname>python35</varname>
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and <varname>pypy</varname>.
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</para>
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<para>
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<varname>python</varname> is an alias to <varname>python27</varname> and <varname>python3</varname> is an alias to <varname>python34</varname>.
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</para>
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<para>
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<varname>python26</varname> and <varname>python27</varname> do not include modules that require
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external dependencies (to reduce dependency bloat). Following modules need to be added as
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<varname>buildInput</varname> explicitly:
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</para>
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<itemizedlist>
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<listitem><para><varname>python.modules.bsddb</varname></para></listitem>
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<listitem><para><varname>python.modules.curses</varname></para></listitem>
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<listitem><para><varname>python.modules.curses_panel</varname></para></listitem>
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<listitem><para><varname>python.modules.crypt</varname></para></listitem>
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<listitem><para><varname>python.modules.gdbm</varname></para></listitem>
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<listitem><para><varname>python.modules.sqlite3</varname></para></listitem>
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<listitem><para><varname>python.modules.tkinter</varname></para></listitem>
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<listitem><para><varname>python.modules.readline</varname></para></listitem>
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</itemizedlist>
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<para>For convenience <varname>python27Full</varname> and <varname>python26Full</varname>
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are provided with all modules included.</para>
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<para>
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Python packages that
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use <link xlink:href="http://pypi.python.org/pypi/setuptools/"><literal>setuptools</literal></link> or <literal>distutils</literal>,
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can be built using the <varname>buildPythonPackage</varname> function as documented below.
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</para>
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<para>
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All packages depending on any Python interpreter get appended <varname>$out/${python.sitePackages}</varname>
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to <literal>$PYTHONPATH</literal> if such directory exists.
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</para>
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<variablelist>
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<title>
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Useful attributes on interpreters packages:
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</title>
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<varlistentry>
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<term><varname>libPrefix</varname></term>
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<listitem><para>
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Name of the folder in <literal>${python}/lib/</literal> for corresponding interpreter.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>interpreter</varname></term>
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<listitem><para>
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Alias for <literal>${python}/bin/${executable}.</literal>
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>buildEnv</varname></term>
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<listitem><para>
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Function to build python interpreter environments with extra packages bundled together.
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See <xref linkend="ssec-python-build-env" /> for usage and documentation.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>sitePackages</varname></term>
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<listitem><para>
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Alias for <literal>lib/${libPrefix}/site-packages</literal>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>executable</varname></term>
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<listitem><para>
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Name of the interpreter executable, ie <literal>python3.4</literal>.
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</para></listitem>
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</varlistentry>
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</variablelist>
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<section xml:id="ssec-build-python-package"><title><varname>buildPythonPackage</varname> function</title>
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<para>
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The function is implemented in <link xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/python-modules/generic/default.nix">
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<filename>pkgs/development/python-modules/generic/default.nix</filename></link>.
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Example usage:
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<programlisting language="nix">
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twisted = buildPythonPackage {
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name = "twisted-8.1.0";
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src = pkgs.fetchurl {
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url = http://tmrc.mit.edu/mirror/twisted/Twisted/8.1/Twisted-8.1.0.tar.bz2;
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sha256 = "0q25zbr4xzknaghha72mq57kh53qw1bf8csgp63pm9sfi72qhirl";
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};
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propagatedBuildInputs = [ self.ZopeInterface ];
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meta = {
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homepage = http://twistedmatrix.com/;
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description = "Twisted, an event-driven networking engine written in Python";
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license = stdenv.lib.licenses.mit;
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};
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};
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</programlisting>
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Most of Python packages that use <varname>buildPythonPackage</varname> are defined
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in <link xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/top-level/python-packages.nix"><filename>pkgs/top-level/python-packages.nix</filename></link>
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and generated for each python interpreter separately into attribute sets <varname>python26Packages</varname>,
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<varname>python27Packages</varname>, <varname>python35Packages</varname>, <varname>python33Packages</varname>,
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<varname>python34Packages</varname> and <varname>pypyPackages</varname>.
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</para>
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<para>
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<function>buildPythonPackage</function> mainly does four things:
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<orderedlist>
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<listitem><para>
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In the <varname>buildPhase</varname>, it calls
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<literal>${python.interpreter} setup.py bdist_wheel</literal> to build a wheel binary zipfile.
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</para></listitem>
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<listitem><para>
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In the <varname>installPhase</varname>, it installs the wheel file using
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<literal>pip install *.whl</literal>.
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</para></listitem>
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<listitem><para>
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In the <varname>postFixup</varname> phase, <literal>wrapPythonPrograms</literal>
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bash function is called to wrap all programs in <filename>$out/bin/*</filename>
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directory to include <literal>$PYTHONPATH</literal> and <literal>$PATH</literal>
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environment variables.
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</para></listitem>
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<listitem><para>
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In the <varname>installCheck</varname> phase, <literal>${python.interpreter} setup.py test</literal>
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is ran.
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</para></listitem>
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</orderedlist>
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</para>
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<para>By default <varname>doCheck = true</varname> is set</para>
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<para>
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As in Perl, dependencies on other Python packages can be specified in the
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<varname>buildInputs</varname> and
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<varname>propagatedBuildInputs</varname> attributes. If something is
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exclusively a build-time dependency, use
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<varname>buildInputs</varname>; if it’s (also) a runtime dependency,
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use <varname>propagatedBuildInputs</varname>.
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</para>
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<para>
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By default <varname>meta.platforms</varname> is set to the same value
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as the interpreter unless overriden otherwise.
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</para>
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<variablelist>
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<title>
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<varname>buildPythonPackage</varname> parameters
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(all parameters from <varname>mkDerivation</varname> function are still supported)
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</title>
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<varlistentry>
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<term><varname>namePrefix</varname></term>
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<listitem><para>
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Prepended text to <varname>${name}</varname> parameter.
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Defaults to <literal>"python3.3-"</literal> for Python 3.3, etc. Set it to
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<literal>""</literal>
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if you're packaging an application or a command line tool.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>disabled</varname></term>
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<listitem><para>
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If <varname>true</varname>, package is not build for
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particular python interpreter version. Grep around
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<filename>pkgs/top-level/python-packages.nix</filename>
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for examples.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>setupPyBuildFlags</varname></term>
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<listitem><para>
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List of flags passed to <command>setup.py build_ext</command> command.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>pythonPath</varname></term>
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<listitem><para>
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List of packages to be added into <literal>$PYTHONPATH</literal>.
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Packages in <varname>pythonPath</varname> are not propagated
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(contrary to <varname>propagatedBuildInputs</varname>).
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>preShellHook</varname></term>
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<listitem><para>
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Hook to execute commands before <varname>shellHook</varname>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>postShellHook</varname></term>
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<listitem><para>
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Hook to execute commands after <varname>shellHook</varname>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>makeWrapperArgs</varname></term>
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<listitem><para>
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A list of strings. Arguments to be passed to
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<varname>makeWrapper</varname>, which wraps generated binaries. By
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default, the arguments to <varname>makeWrapper</varname> set
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<varname>PATH</varname> and <varname>PYTHONPATH</varname> environment
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variables before calling the binary. Additional arguments here can
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allow a developer to set environment variables which will be
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available when the binary is run. For example,
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<varname>makeWrapperArgs = ["--set FOO BAR" "--set BAZ QUX"]</varname>.
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</para></listitem>
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</varlistentry>
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</variablelist>
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</section>
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<section xml:id="ssec-python-build-env"><title><function>python.buildEnv</function> function</title>
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<para>
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Create Python environments using low-level <function>pkgs.buildEnv</function> function. Example <filename>default.nix</filename>:
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<programlisting language="nix">
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<![CDATA[with import <nixpkgs> {};
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python.buildEnv.override {
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extraLibs = [ pkgs.pythonPackages.pyramid ];
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ignoreCollisions = true;
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}]]>
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</programlisting>
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Running <command>nix-build</command> will create
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<filename>/nix/store/cf1xhjwzmdki7fasgr4kz6di72ykicl5-python-2.7.8-env</filename>
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with wrapped binaries in <filename>bin/</filename>.
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</para>
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<para>
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You can also use <varname>env</varname> attribute to create local
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environments with needed packages installed (somewhat comparable to
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<literal>virtualenv</literal>). For example, with the following
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<filename>shell.nix</filename>:
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<programlisting language="nix">
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<![CDATA[with import <nixpkgs> {};
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(python3.buildEnv.override {
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extraLibs = with python3Packages;
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[ numpy
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requests
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];
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}).env]]>
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</programlisting>
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Running <command>nix-shell</command> will drop you into a shell where
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<command>python</command> will have specified packages in its path.
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</para>
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<variablelist>
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<title>
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<function>python.buildEnv</function> arguments
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</title>
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<varlistentry>
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<term><varname>extraLibs</varname></term>
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<listitem><para>
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List of packages installed inside the environment.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>postBuild</varname></term>
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<listitem><para>
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Shell command executed after the build of environment.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>ignoreCollisions</varname></term>
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<listitem><para>
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Ignore file collisions inside the environment (default is <varname>false</varname>).
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</para></listitem>
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</varlistentry>
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</variablelist>
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</section>
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<section xml:id="ssec-python-tools"><title>Tools</title>
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<para>Packages inside nixpkgs are written by hand. However many tools
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exist in community to help save time. No tool is preferred at the moment.
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</para>
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<itemizedlist>
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<listitem><para>
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<link xlink:href="https://github.com/proger/python2nix">python2nix</link>
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by Vladimir Kirillov
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</para></listitem>
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<listitem><para>
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<link xlink:href="https://github.com/garbas/pypi2nix">pypi2nix</link>
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by Rok Garbas
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</para></listitem>
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<listitem><para>
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<link xlink:href="https://github.com/offlinehacker/pypi2nix">pypi2nix</link>
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by Jaka Hudoklin
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</para></listitem>
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</itemizedlist>
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</section>
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<section xml:id="ssec-python-development"><title>Development</title>
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<para>
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To develop Python packages <function>buildPythonPackage</function> has
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additional logic inside <varname>shellPhase</varname> to run
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<command>pip install -e . --prefix $TMPDIR/</command> for the package.
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</para>
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<warning><para><varname>shellPhase</varname> is executed only if <filename>setup.py</filename>
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exists.</para></warning>
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<para>
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Given a <filename>default.nix</filename>:
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<programlisting language="nix">
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<![CDATA[with import <nixpkgs> {};
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buildPythonPackage {
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name = "myproject";
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buildInputs = with pkgs.pythonPackages; [ pyramid ];
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src = ./.;
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}]]>
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</programlisting>
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Running <command>nix-shell</command> with no arguments should give you
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the environment in which the package would be build with
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<command>nix-build</command>.
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</para>
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<para>
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Shortcut to setup environments with C headers/libraries and python packages:
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<programlisting language="bash">$ nix-shell -p pythonPackages.pyramid zlib libjpeg git</programlisting>
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</para>
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<note><para>
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There is a boolean value <varname>lib.inNixShell</varname> set to
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<varname>true</varname> if nix-shell is invoked.
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</para></note>
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</section>
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<section xml:id="ssec-python-faq"><title>FAQ</title>
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<variablelist>
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<varlistentry>
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<term>How to solve circular dependencies?</term>
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||
<listitem><para>
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If you have packages <varname>A</varname> and <varname>B</varname> that
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depend on each other, when packaging <varname>B</varname> override package
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<varname>A</varname> not to depend on <varname>B</varname> as input
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(and also the other way around).
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>install_data / data_files</varname> problems resulting into <literal>error: could not create '/nix/store/6l1bvljpy8gazlsw2aw9skwwp4pmvyxw-python-2.7.8/etc': Permission denied</literal></term>
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<listitem><para>
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||
<link xlink:href="https://bitbucket.org/pypa/setuptools/issue/130/install_data-doesnt-respect-prefix">
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||
Known bug in setuptools <varname>install_data</varname> does not respect --prefix</link>. Example of
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||
such package using the feature is <filename>pkgs/tools/X11/xpra/default.nix</filename>. As workaround
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||
install it as an extra <varname>preInstall</varname> step:
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||
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<programlisting>${python.interpreter} setup.py install_data --install-dir=$out --root=$out
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sed -i '/ = data_files/d' setup.py</programlisting>
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||
</para></listitem>
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||
</varlistentry>
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||
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||
<varlistentry>
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||
<term>Rationale of non-existent global site-packages</term>
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||
<listitem><para>
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||
There is no need to have global site-packages in Nix. Each package has isolated
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||
dependency tree and installing any python package will only populate <varname>$PATH</varname>
|
||
inside user environment. See <xref linkend="ssec-python-build-env" /> to create self-contained
|
||
interpreter with a set of packages.
|
||
</para></listitem>
|
||
</varlistentry>
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||
|
||
</variablelist>
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||
|
||
</section>
|
||
|
||
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||
<section xml:id="ssec-python-contrib"><title>Contributing guidelines</title>
|
||
<para>
|
||
Following rules are desired to be respected:
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||
</para>
|
||
|
||
<itemizedlist>
|
||
|
||
<listitem><para>
|
||
Make sure package builds for all python interpreters. Use <varname>disabled</varname> argument to
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||
<function>buildPythonPackage</function> to set unsupported interpreters.
|
||
</para></listitem>
|
||
|
||
<listitem><para>
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||
If tests need to be disabled for a package, make sure you leave a comment about reasoning.
|
||
</para></listitem>
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||
|
||
<listitem><para>
|
||
Packages in <link xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/top-level/python-packages.nix"><filename>pkgs/top-level/python-packages.nix</filename></link>
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||
are sorted quasi-alphabetically to avoid merge conflicts.
|
||
</para></listitem>
|
||
|
||
</itemizedlist>
|
||
|
||
</section>
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||
|
||
</section>
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||
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