source: general/prog/python3.xml@ 7b66ed2

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;

  <!ENTITY python3-download-http
           "https://www.python.org/ftp/python/&python3-version;/Python-&python3-version;.tar.xz">
  <!ENTITY python3-download-ftp  " ">
  <!ENTITY python3-md5sum        "f0dc9000312abeb16de4eccce9a870ab">
  <!ENTITY python3-size          "18 MB">
  <!ENTITY python3-buildsize     "379 MB (add 36 MB for tests)">
  <!ENTITY python3-time          "0.5 SBU (using parallelism=4; add 1.7 SBU for tests)">
  <!--
  Note: Size does not reflect docs that were install in LFS.

  <!ENTITY python3htmldoc-download-http
  "https://docs.python.org/ftp/python/doc/&python3-version;/python-&python3-version;-docs-html.tar.bz2"> -->
]>

<sect1 id="python3" xreflabel="Python-&python3-version;">
  <?dbhtml filename="python3.html" ?>

  <sect1info>
    <othername>$LastChangedBy$</othername>
    <date>$Date$</date>
  </sect1info>

  <title>Python-&python3-version;</title>

  <indexterm zone="python3">
    <primary sortas="a-Python3">Python3</primary>
  </indexterm>

  <sect2 role="package">
    <title>Introduction to Python 3</title>

    <para>
      The <application>Python 3</application> package contains the
      <application>Python</application> development environment.
      This is useful for object-oriented programming, writing scripts,
      prototyping large programs or developing entire applications.
    </para>

    <note>
      <para>
        <application>Python 3</application> was installed in LFS.
        The only reason to rebuild it here is if optional modules
        are needed.
      </para>
    </note>

    &lfs101_checked;

    <bridgehead renderas="sect3">Package Information</bridgehead>
    <itemizedlist spacing="compact">
      <listitem>
        <para>
          Download (HTTP): <ulink url="&python3-download-http;"/>
        </para>
      </listitem>
      <listitem>
        <para>
          Download (FTP): <ulink url="&python3-download-ftp;"/>
        </para>
      </listitem>
      <listitem>
        <para>
          Download MD5 sum: &python3-md5sum;
        </para>
      </listitem>
      <listitem>
        <para>
          Download size: &python3-size;
        </para>
      </listitem>
      <listitem>
        <para>
          Estimated disk space required: &python3-buildsize;
        </para>
      </listitem>
      <listitem>
        <para>
          Estimated build time: &python3-time;
        </para>
      </listitem>
    </itemizedlist>

    <bridgehead renderas="sect3">Python 3 Dependencies</bridgehead>

    <bridgehead renderas="sect4">Recommended</bridgehead>
    <para role="recommended">
      <xref linkend="sqlite"/> (required if building firefox or thunderbird)
    </para>

    <bridgehead renderas="sect4">Optional</bridgehead>
    <para role="optional">
      <xref linkend="bluez"/>,
      <xref linkend="gdb"/> (required for some tests),
      <xref linkend="valgrind"/>, and
      <ulink url="http://www.bytereef.org/mpdecimal">libmpdec</ulink>
    </para>

    <bridgehead renderas="sect4">Optional (For Additional Modules)</bridgehead>
    <para role="optional">
      <xref linkend="db"/> and
      <xref linkend="tk"/>
    </para>

    <para condition="html" role="usernotes">User Notes:
      <ulink url="&blfs-wiki;/Python3"/>
    </para>
  </sect2>

  <sect2 role="installation">
    <title>Installation of Python 3</title>

    <para>
      Fix a header file, which is needed for some use cases:
    </para>

<screen><userinput>sed 's|cpython/||' -i Include/cpython/pystate.h</userinput></screen>

    <para>
      Install <application>Python 3</application> by running the following
      commands:
    </para>

<screen><userinput>CXX="/usr/bin/g++"              \
./configure --prefix=/usr       \
            --enable-shared     \
            --with-system-expat \
            --with-system-ffi   \
            --with-ensurepip=yes &amp;&amp;
make</userinput></screen>

    <para>
      To test the result, issue <command>make test</command>.
      Some tests may need Internet connection.
    </para>

    <para>
      Now, as the <systemitem class="username">root</systemitem> user:
    </para>

<screen role="root"><userinput>make install</userinput></screen>

  </sect2>

  <sect2 role="commands">
    <title>Command Explanations</title>

    <para>
      <command> CXX="/usr/bin/g++" ./configure ...</command>: Avoid an annoying
      message during configuration.
    </para>

    <para>
      <parameter>--with-system-expat</parameter>: This switch enables linking
      against the system version of <application>Expat</application>.
    </para>

    <para>
      <parameter>--with-system-ffi</parameter>: This switch enables linking
      against system version of <application>libffi</application>. 
    </para>

    <para>
      <parameter>--with-ensurepip=yes</parameter> : This switch enables building
      <command>pip</command> and <command>setuptools</command> packaging programs.
      <command>setuptools</command> is needed for building some Python modules.
    </para>

    <para>
      <option>--with-dbmliborder=bdb:gdbm:ndbm</option>: Use this switch
      if you want to build <application>Python</application> DBM Module
      against <application>Berkeley DB</application> instead of
      <application>GDBM</application>.
    </para>

    <para>
      <option>--enable-optimization</option>: Use this switch
      if you want to enable <emphasis>expensive</emphasis> optimizations (i.e.
      Profile Guided Optimizations). This adds around 20 SBU, but can
      <emphasis>slightly</emphasis> speed up some uses, such as using
      <application>Sphinx</application> for creating documentation, or use of
      <application>Python3</application> scripts.
    </para>

    <para>
      <option>--with-lto</option>: This optional switch enables thick Link
      Time Optimization. Unusually, it creates a much larger <filename
          class="libraryfile">/usr/lib/python&python3-majorver;/config-&python3-majorver;-&lt;arch&gt;-linux-gnu/libpython&python3-majorver;.a</filename>
      with a small increase in the time to compile
      <application>Python</application>. Run-time results do not appear to show
      any benefit from doing this.
    </para>
    <!--
    <para>
      <command>ln -sfv ...</command>: When upgrading to Python-3.8, it was
      discovered that the symlink to pip3 is sometimes not created. Create
      the symlink so that pip3 can be used as described in the book.
    </para>
    -->

  </sect2>

  <sect2 role="configuration">
    <title>Configuring Python 3</title>

    <para>
      In order for <command>python3</command> to find the installed
      documentation, create the following version independent symlink:
    </para>

<screen role="root"><userinput>ln -svfn python-&python3-version; /usr/share/doc/python-3</userinput></screen>

    <para>
      and add the following environment variable to the individual user's or
      system's profile:
    </para>

<screen role="root"><userinput>export PYTHONDOCS=/usr/share/doc/python-3/html</userinput></screen>

  </sect2>

  <sect2 role="content">
    <title>Contents</title>

    <segmentedlist>
      <segtitle>Installed Programs</segtitle>
      <segtitle>Installed Libraries</segtitle>
      <segtitle>Installed Directories</segtitle>

      <seglistitem>
        <seg>
          2to3 (symlink) and
          2to3-&python3-majorver;,

          easy_install-&python3-majorver;,

          idle3 (symlink) and
          idle&python3-majorver;,

          pip3 (symlink) and
          pip&python3-majorver;,

          pydoc3 and
          pydoc&python3-majorver;,

          python3 (symlink);
          python&python3-majorver;, and

          python3 (symlink), and
          python&python3-majorver;

          python3-config (symlink) and
          python&python3-majorver;-config
        </seg>
        <seg>
          libpython&python3-majorver;.so and libpython3.so
        </seg>
        <seg>
          /usr/include/python&python3-majorver;,
          /usr/lib/python&python3-majorver;, and
          /usr/share/doc/python-&python3-version;
        </seg>
      </seglistitem>
    </segmentedlist>

    <variablelist>
      <bridgehead renderas="sect3">Short Descriptions</bridgehead>
      <?dbfo list-presentation="list"?>
      <?dbhtml list-presentation="table"?>
      <!--
      <varlistentry id="2to3">
        <term><command>2to3</command></term>
        <listitem>
          <para>
            is designed to assist in the transition between python2 and python3
            by automatically converting code to be Python3 compatible.
          </para>
          <indexterm zone="python3 2to3">
            <primary sortas="b-2to3">2to3</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      Put here for easy use when removing Python2 -->
      <varlistentry id="easy_install">
        <term><command>easy_install</command></term>
        <listitem>
          <para>
            is a frontend to pip3 to make it easier to configure python modules
            through the PIP package manager
          </para>
          <indexterm zone="python3 easy_install">
            <primary sortas="python3 easy_install">easy_install</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="idle3">
        <term><command>idle3</command></term>
        <listitem>
          <para>
            is a wrapper script that opens a <application>Python</application>
            aware GUI editor. For this script to run, you must have installed
            <application>Tk</application> before Python so that the Tkinter
            Python module is built
          </para>
          <indexterm zone="python3 idle3">
            <primary sortas="b-idle3">idle3</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="pydoc3">
        <term><command>pydoc3</command></term>
        <listitem>
          <para>
            is the <application>Python</application> documentation
            tool
          </para>
          <indexterm zone="python3 pydoc3">
            <primary sortas="b-pydoc3">pydo3c</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="python3-prog">
        <term><command>python3</command></term>
        <listitem>
          <para>
            is an interpreted, interactive, object-oriented programming
            language
          </para>
          <indexterm zone="python3 python3-prog">
            <primary sortas="b-python3">python3</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="python-ver">
        <term><command>python&python3-majorver;</command></term>
        <listitem>
          <para>
            is a version-specific name for the <command>python</command>
            program
          </para>
          <indexterm zone="python3 python-ver">
            <primary sortas="b-python&python3-majorver;">python&python3-majorver;</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      <!--
      <varlistentry id="pyvenv">
        <term><command>pyvenv</command></term>
        <listitem>
          <para>
            creates virtual <application>Python</application> environments in
            one or more target directories.
          </para>
          <indexterm zone="python3 pyvenv">
            <primary
            sortas="b-python&python3-majorver;">python&python3-majorver;</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      -->
    </variablelist>

  </sect2>

</sect1>