<refentry id="glib-building" revision="16 Jan 2002">
<refmeta>
<refentrytitle>Compiling the GLib package</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>GLib Library</refmiscinfo>
</refmeta>

<refnamediv>
<refname>Compiling the GLib Package</refname>
<refpurpose>
How to compile GLib itself
</refpurpose>
  </refnamediv>

    <refsect1 id="building">
      <title>Building the Library on UNIX</title>
      <para>
        On UNIX, GLib uses the standard GNU build system,
        using <application>autoconf</application> for package
        configuration and resolving portability issues,
        <application>automake</application> for building makefiles
        that comply with the GNU Coding Standards, and
        <application>libtool</application> for building shared
        libraries on multiple platforms.  The normal sequence for
        compiling and installing the GLib library is thus:

        <literallayout>
          <userinput>./configure</userinput>
          <userinput>make</userinput>
          <userinput>make install</userinput>
        </literallayout>
      </para>

      <para>
        The standard options provided by <application>GNU
        autoconf</application> may be passed to the
        <command>configure</command> script.  Please see the
        <application>autoconf</application> documentation or run
        <command>./configure --help</command> for information about
        the standard options.
      </para>
      <para>
        The GTK+ documentation contains 
        <ulink url="../gtk/gtk-building.html">further details</ulink> 
	about the build process and ways to influence it. 
      </para>
    </refsect1>
    <refsect1 id="dependencies">
      <title>Dependencies</title>
      <para>
        Before you can compile the GLib library, you need to have
        various other tools and libraries installed on your
        system. The two tools needed during the build process (as
        differentiated from the tools used in when creating GLib
        mentioned above such as <application>autoconf</application>)
        are <command>pkg-config</command> and GNU make.
      </para>
      <itemizedlist>
        <listitem>
   	  <para>
	    <ulink
	    url="http://www.freedesktop.org/software/pkgconfig/">pkg-config</ulink>
	    is a tool for tracking the compilation flags needed for
	    libraries that are used by the GLib library. (For each
	    library, a small <literal>.pc</literal> text file is 
            installed in a standard location that contains the compilation 
            flags needed for that library along with version number 
            information.)  The version of <command>pkg-config</command> 
            needed to build GLib is mirrored in the 
	    <filename>dependencies</filename> directory
	    on the <ulink url="ftp://ftp.gtk.org/pub/gtk/v2.2/">GTK+ FTP
	    site.</ulink>
	  </para>
        </listitem>
        <listitem>
	  <para>
	    The GTK+ makefiles will mostly work with different versions
	    of <command>make</command>, however, there tends to be
	    a few incompatibilities, so the GTK+ team recommends
	    installing <ulink url="http://www.gnu.org/software/make">GNU
	    make</ulink> if you don't already have it on your system
	    and using it. (It may be called <command>gmake</command>
	    rather than <command>make</command>.)
	  </para>
        </listitem>
      </itemizedlist>
      <para>
        GLib depends on a number of other libraries.
      </para>
      <itemizedlist>
        <listitem>
	  <para>
	  The <ulink url="http://www.gnu.org/software/libiconv/">GNU
	  libiconv library</ulink> is needed to build GLib if your
	  system doesn't have the <function>iconv()</function>
	  function for doing conversion between character
	  encodings. Most modern systems should have
	  <function>iconv()</function>, however many older systems lack 
	  an <function>iconv()</function> implementation. On such systems, 
	  you must install the libiconv library. This can be found at:
	  <ulink url="http://www.gnu.org/software/libiconv">http://www.gnu.org/software/libiconv</ulink>.	  
	</para>
        <para>
	  If your system has an <function>iconv()</function> implementation but
	  you want to use libiconv instead, you can pass the
	  --with-libiconv option to configure. This forces
	  libiconv to be used.  
	</para>
        <para>
	  Note that if you have libiconv installed in your default include
	  search path (for instance, in <filename>/usr/local/</filename>), but
	  don't enable it, you will get an error while compiling GLib because
	  the <filename>iconv.h</filename> that libiconv installs hides the
	  system iconv. 
	</para>
	<para>
	  If you are using the native iconv implementation on Solaris
	  instead of libiconv, you'll need to make sure that you have 
	  the converters between locale encodings and UTF-8 installed.
	  At a minimum you'll need the SUNWuiu8 package. You probably
	  should also install the SUNWciu8, SUNWhiu8, SUNWjiu8, and
	  SUNWkiu8 packages.
	</para>
	<para>
	  The native iconv on Compaq Tru64 doesn't contain support for
	  UTF-8, so you'll need to use GNU libiconv instead. (When
	  using GNU libiconv for GLib, you'll need to use GNU libiconv
	  for GNU gettext as well.) This probably applies to related
	  operating systems as well.
	</para>
      </listitem>
      <listitem>
	<para>
	  The libintl library from the <ulink
	  url="http://www.gtk.org/software/gettext">GNU gettext
	  package</ulink> is needed if your system doesn't have the
	  <function>gettext()</function> functionality for handling
	  message translation databases.
	</para>
      </listitem>
      <listitem>
	<para>
	  A thread implementation is needed, unless you want to compile GLib
	  without thread support, which is not recommended. The thread support
	  in GLib can be based upon several native thread implementations,
	  e.g. POSIX threads, DCE threads or Solaris threads. 
	</para>
      </listitem>
    </itemizedlist>

    </refsect1>
    <refsect1 id="extra-configuration-options">
      <title>Extra Configuration Options</title>

      <para>
        In addition to the normal options, the
        <command>configure</command> script in the GLib
        library supports these additional arguments:

        <cmdsynopsis>
          <command>configure</command>
          <group>
            <arg>--enable-debug=[no|minimum|yes]</arg>
          </group>
          <group>
            <arg>--disable-gc-friendly</arg>
            <arg>--enable-gc-friendly</arg>
          </group>
          <group>
            <arg>--disable-mem-pools</arg>
            <arg>--enable-mem-pools</arg>
          </group>
          <group>
            <arg>--disable-threads</arg>
            <arg>--enable-threads</arg>
          </group>
          <group>
            <arg>--with-threads=[none|posix|dce|win32]</arg>
          </group>
	  <group>
             <arg>--disable-included-printf</arg>
             <arg>--enable-included-printf</arg>
          </group>
	  <group>
             <arg>--disable-visibility</arg>
             <arg>--enable-visibility</arg>
          </group>
          <group>
            <arg>--disable-gtk-doc</arg>
            <arg>--enable-gtk-doc</arg>
          </group>
          <group>
            <arg>--disable-man</arg>
            <arg>--enable-man</arg>
          </group>
        </cmdsynopsis>
      </para>

      <formalpara>
        <title><systemitem>--enable-debug</systemitem></title>

        <para>
         Turns on various amounts of debugging support. Setting this to 'no'
         disables g_assert(), g_return_if_fail(), g_return_val_if_fail() and
         all cast checks between different object types. Setting it to 'minimum'         disables only cast checks. Setting it to 'yes' enables
         <link linkend="GLIB-Debug-Options">runtime debugging</link>.
         The default is 'minimum'.
         Note that 'no' is fast, but dangerous as it tends to destabilize
         even mostly bug-free software by changing the effect of many bugs
         from simple warnings into fatal crashes. Thus
         <option>--enable-debug=no</option> should <emphasis>not</emphasis>
         be used for stable releases of GLib.
        </para>
      </formalpara>

      <formalpara>
        <title><systemitem>--disable-gc-friendly</systemitem> and
          <systemitem>--enable-gc-friendly</systemitem></title>

        <para>
	  By default, and with <systemitem>--disable-gc-friendly</systemitem>
	  as well, Glib does not clear the memory for certain objects before they
	  are freed.  For example, Glib may decide to recycle GList nodes by
	  putting them in a free list.  However, memory profiling and debugging tools like <ulink
	  url="http://www.valgrind.org">Valgrind</ulink> work better if an
	  application does not keep dangling pointers to freed memory (even
	  though these pointers are no longer dereferenced), or invalid pointers inside
	  uninitialized memory.   The
	  <systemitem>--enable-gc-friendly</systemitem> option makes Glib clear
	  memory in these situations:
        </para>
      </formalpara>

      <itemizedlist>
        <listitem>
	  <para>
	    When shrinking a GArray, Glib will clear the memory no longer
	    available in the array:  shrink an array from 10 bytes to 7, and
	    the last 3 bytes will be cleared.  This includes removals of single and multiple elements.
	  </para>
        </listitem>
        <listitem>
	  <para>
	  </para>
        </listitem>
        <listitem>
	  <para>
	    When growing a GArray, Glib will clear the new chunk of memory.  
	    Grow an array from 7 bytes to 10 bytes, and the last 3 bytes will be cleared.
	  </para>
        </listitem>
        <listitem>
	  <para>
	    The above applies to GPtrArray as well.
	  </para>
        </listitem>
        <listitem>
	  <para>
	    When freeing a node from a GHashTable, Glib will first clear
	    the node, which used to have pointers to the key and the value 
	    stored at that node.
	  </para>
        </listitem>
        <listitem>
	  <para>
	    When destroying or removing a GTree node, Glib will clear the node,
	    which used to have pointers to the node's value, and the left and right subnodes.
	  </para>
        </listitem>
      </itemizedlist>

      <para>
        Since clearing the memory has a cost,
        <systemitem>--disable-gc-friendly</systemitem> is the default.
      </para>

      <formalpara>
        <title><systemitem>--disable-mem-pools</systemitem> and
          <systemitem>--enable-mem-pools</systemitem></title>

      <para>
        Many small chunks of memory are often allocated via collective pools
        in GLib and are cached after release to speed up reallocations.
        For sparse memory systems this behaviour is often inferior, so
        memory pools can be disabled to avoid excessive caching and force
        atomic maintenance of chunks through the <function>g_malloc()</function>
        and <function>g_free()</function> functions. Code currently affected by 
        this:
        <itemizedlist>
        <listitem>
        <para>
         <structname>GList</structname>, <structname>GSList</structname>,
         <structname>GNode</structname>, <structname>GHash</structname> 
         allocations. The functions g_list_push_allocator(), 
         g_list_pop_allocator(), g_slist_push_allocator(), 
         g_slist_pop_allocator(), g_node_push_allocator() and 
         g_node_pop_allocator() are not available
        </para>
        </listitem>
        <listitem>
        <para>
        <structname>GMemChunk</structname>s become basically non-effective
        </para>
        </listitem>
        <listitem>
        <para>
         <structname>GSignal</structname> disables all caching (potentially 
         very slow)
        </para>
        </listitem>
        <listitem>
        <para>
         <structname>GType</structname> doesn't honour the 
         <structname>GTypeInfo</structname> 
         <structfield>n_preallocs</structfield> field anymore
        </para>
        </listitem>
        <listitem>
        <para>
         the <structname>GBSearchArray</structname> flag 
         <literal>G_BSEARCH_ALIGN_POWER2</literal> becomes non-functional
        </para>
        </listitem>
        </itemizedlist>
      </para>
      </formalpara>

      <formalpara>
        <title><systemitem>--disable-threads</systemitem> and
          <systemitem>--enable-threads</systemitem></title>

        <para>
           Do not compile GLib to be multi thread safe. GLib
           will be slightly faster then. This is however not
           recommended, as many programs rely on GLib being
           multi thread safe.
        </para>
      </formalpara>

      <formalpara>
        <title><systemitem>--with-threads</systemitem></title>

        <para>
          Specify a thread implementation to use.
          <itemizedlist>
              <listitem><para>
                'posix' and 'dce' can be used interchangeable
                to mean the different versions of Posix
                threads. configure tries to find out, which
                one is installed.
              </para></listitem>

              <listitem><para>
                'none' means that GLib will be thread safe,
                but does not have a default thread
                implementation. This has to be supplied to
                <function>g_thread_init()</function> by the programmer.
              </para></listitem>
        </itemizedlist>

        </para>
      </formalpara>

      <formalpara>
         <title><systemitem>--disable-included-printf</systemitem> and
           <systemitem>--enable-included-printf</systemitem></title>

        <para>
          By default the <command>configure</command> script will try
          to auto-detect whether the C library provides a suitable set
	  of <function>printf()</function> functions. In detail, 
	  <command>configure</command> checks that the semantics of
          <function>snprintf()</function> are as specified by C99 and
	  that positional parameters as specified in the Single Unix
	  Specification are supported. If this not the case, GLib will
	  include an implementation of the <function>printf()</function> 
          family.
          These options can be used to explicitly control whether
          an implementation fo the <function>printf()</function> family
          should be included or not.
        </para>
      </formalpara>

      <formalpara>
         <title><systemitem>--disable-visibility</systemitem> and
           <systemitem>--enable-visibility</systemitem></title>

        <para>
          By default, GLib uses ELF visibility attributes to optimize
          PLT table entries if the compiler supports ELF visibility
          attributes. A side-effect of the way in which this is currently
          implemented is that any  header change forces a full 
          recompilation, and missing includes may go unnoticed. 
          Therefore, it makes sense to turn this feature off while
          doing GLib development, even if the compiler supports ELF
          visibility attributes. The <option>--disable-visibility</option> 
          option allows to do that.
        </para>
      </formalpara>

      <formalpara>
        <title><systemitem>--disable-gtk-doc</systemitem> and
          <systemitem>--enable-gtk-doc</systemitem></title>

        <para>
          By default the <command>configure</command> script will try
          to auto-detect whether the
          <application>gtk-doc</application> package is installed.  If
          it is, then it will use it to extract and build the
          documentation for the GLib library.  These options
          can be used to explicitly control whether
          <application>gtk-doc</application> should be
          used or not.  If it is not used, the distributed,
          pre-generated HTML files will be installed instead of
          building them on your machine.
        </para>
      </formalpara>

      <formalpara>
        <title><systemitem>--disable-man</systemitem> and
          <systemitem>--enable-man</systemitem></title>

        <para>
          By default the <command>configure</command> script will try
          to auto-detect whether <application>xsltproc</application> 
          and the necessary Docbook stylesheets are installed.  If
          they are, then it will use them to rebuild the included
          man pages from the XML sources.  These options can be used 
          to explicitly control whether man pages should be rebuilt
          used or not. The distribution includes pre-generated man 
          pages.
        </para>
      </formalpara>

   </refsect1>

</refentry>