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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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<refentry id="glib-compiling" revision="17 Jan 2002">
<refmeta>
<refentrytitle>Compiling GLib Applications</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>GLib Library</refmiscinfo>
</refmeta>

<refnamediv>
<refname>Compiling GLib Applications</refname>
<refpurpose>
How to compile your GLib application
</refpurpose>
</refnamediv>

<refsect1>
<title>Compiling GLib Applications on UNIX</title>

<para>
To compile a GLib application, you need to tell the compiler where to
find the GLib header files and libraries. This is done with the
<application>pkg-config</application> utility.
</para>
<para>
The following interactive shell session demonstrates how
<application>pkg-config</application> is used (the actual output on
your system may be different):
<programlisting>
$ pkg-config --cflags glib-2.0
 -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include
$ pkg-config --libs glib-2.0
 -L/usr/lib -lm -lglib-2.0
</programlisting>
</para>
<para>
See the <ulink url="http://www.freedesktop.org/wiki/Software/pkg-config">pkg-config website</ulink>
for more information about <application>pkg-config</application>.
</para>
<para>
If your application uses or <structname>GObject</structname>
features, it must be compiled and linked with the options returned
by the following <application>pkg-config</application> invocation:
<programlisting>
$ pkg-config --cflags --libs gobject-2.0
</programlisting>
</para>
<para>
If your application uses modules, it must be compiled and linked
with the options returned by one of the following
<application>pkg-config</application> invocations:
<programlisting>
$ pkg-config --cflags --libs gmodule-no-export-2.0
$ pkg-config --cflags --libs gmodule-2.0
</programlisting>
The difference between the two is that gmodule-2.0 adds
<option>--export-dynamic</option> to the linker flags,
which is often not needed.
</para>
<para>
The simplest way to compile a program is to use the "backticks"
feature of the shell. If you enclose a command in backticks
(<emphasis>not single quotes</emphasis>), then its output will
be substituted into the command line before execution. So to
compile a GLib Hello, World, you would type the following:
<programlisting>
$ cc hello.c `pkg-config --cflags --libs glib-2.0` -o hello
</programlisting>
</para>
<note><para>
Note that the name of the file must come before the other options
(such as <emphasis>pkg-config</emphasis>), or else you may get an
error from the linker.
</para></note>

<para>
Deprecated GLib functions are annotated to make the compiler
emit warnings when they are used (e.g. with gcc, you need to use
the -Wdeprecated-declarations option). If these warnings are
problematic, they can be turned off by defining the preprocessor
symbol <link linkend="GLIB-DISABLE-DEPRECATION-WARNINGS:CAPS"><literal>GLIB_DISABLE_DEPRECATION_WARNINGS</literal></link> by using the commandline
option <literal>-DGLIB_DISABLE_DEPRECATION_WARNINGS</literal>
</para>

<para>
GLib deprecation annotations are versioned; by defining the
macros <link linkend="GLIB-VERSION-MIN-REQUIRED:CAPS"><literal>GLIB_VERSION_MIN_REQUIRED</literal></link> and <link linkend="GLIB-VERSION-MAX-ALLOWED:CAPS"><literal>GLIB_VERSION_MAX_ALLOWED</literal></link>,
you can specify the range of GLib versions whose API you want
to use. APIs that were deprecated before or introduced after
this range will trigger compiler warnings.
</para>

<para>
Since GLib 2.62, the older deprecation mechanism of hiding deprecated interfaces
entirely from the compiler by using the preprocessor symbol
<literal>G_DISABLE_DEPRECATED</literal> has been removed. All deprecations
are now handled using the above mechanism.
</para>

<para>
The recommended way of using GLib has always been to only include the
toplevel headers <filename>glib.h</filename>,
<filename>glib-object.h</filename>, <filename>gio.h</filename>.
Starting with 2.32, GLib enforces this by generating an error
when individual headers are directly included.
</para>

<para>
Still, there are some exceptions; these headers have to be included
separately:
<filename>gmodule.h</filename>,
<filename>glib-unix.h</filename>,
<filename>glib/gi18n-lib.h</filename> or
<filename>glib/gi18n.h</filename> (see
the <link linkend="glib-I18N">Internationalization section</link>),
<filename>glib/gprintf.h</filename> and
<filename>glib/gstdio.h</filename>
(we don't want to pull in all of stdio).
</para>

</refsect1>

</refentry>
