<tr>              <td><pre class="PROGRAMLISTING">&#13;static voidsave_column_order(const vector&lt;GAptPkgTree::ColumnType&gt; &amp; columns){  g_return_if_fail(columns.size() ==                    static_cast&lt;guint&gt;(GAptPkgTree::ColumnTypeEnd));  int position = 0;  vector&lt;GAptPkgTree::ColumnType&gt;::const_iterator i = columns.begin();  while (i != columns.end())    {      gchar key[256];      g_snprintf(key, 255, "/gnome-apt/ColumnOrder/%s", column_to_string(*i));      gchar val[30];      g_snprintf(val, 29, "%d", position);      gnome_config_set_string(key, val);            ++position;      ++i;    }  gnome_config_sync();}&#13;</pre>              </td>            </tr>          </table>          <p>            When writing this code, the decision was made to store            enumeration values as strings rather than integers. The            <tt class="FUNCTION">column_to_string()</tt> and <tt            class="FUNCTION">string_to_column()</tt> functions use            a simple array of column names indexed by the            enumeration values to convert back and forth. There are            two reasons to do this: it will not break when the            enumeration is altered in future versions of the            program, and it keeps the configuration file            human-editable.          </p>          <p>            You may also notice that the column positions are            stored with <tt class="FUNCTION">            gnome_config_set_string()</tt> instead of <tt class=             "FUNCTION">gnome_config_set_int()</tt>. This is because            <tt class="FUNCTION">gnome_config_iterator_next()</tt>            returns a string representation of the stored            information, as found in the file. Most likely, <tt            class="FUNCTION">gnome_config_set_int()</tt> stores            integers as strings <tt class="FUNCTION">atoi()</tt>            would understand (in fact it does), but it is            technically not guaranteed by the API. If the code used            <tt class="FUNCTION">gnome_config_set_int()</tt>, it            would have to obtain only the key from <tt class=             "FUNCTION">gnome_config_iterator_next()</tt> and then            call <tt class="FUNCTION">gnome_config_get_int()</tt>            to obtain the integer value. Using <tt class=            "FUNCTION">atoi()</tt> on the string value would make            unwarranted assumptions about <tt class="APPLICATION">            gnome-config</tt>'s implementation.          </p>        </div>        <div class="SECT3">          <h3 class="SECT3">            <a name="Z84">Section Iterators</a>          </h3>          <p>            <tt class="FUNCTION">            gnome_config_init_iterator_sections()</tt> allows you            to iterate over the sections in a file, rather than            over the keys in a section. When iterating over            sections, <tt class="FUNCTION">            gnome_config_iterator_next()</tt> ignores its <span            class="STRUCTNAME">value</span> argument and places the            section name in the <span class="STRUCTNAME">key</span>            argument.          </p>          <div class="FIGURE">            <a name="STARTUP-GNOMECONFIGITERATORS"></a>            <div class="FUNCSYNOPSIS">              <a name="STARTUP-GNOMECONFIGITERATORS.SYNOPSIS"></a>              <table border="0" bgcolor="#E0E0E0" width="100%">                <tr>                  <td><pre class="FUNCSYNOPSISINFO">#include &lt;libgnome/gnome-config.h&gt;</pre>                  </td>                </tr>              </table>              <p>                <code><code class="FUNCDEF">void* <tt class=                 "FUNCTION">                gnome_config_init_iterator</tt></code>(const gchar*                <tt class="PARAMETER"><i>path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void* <tt class=                 "FUNCTION">                gnome_config_private_init_iterator</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void* <tt class=                 "FUNCTION">                gnome_config_init_iterator_sections</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void* <tt class=                 "FUNCTION">                gnome_config_private_init_iterator_sections</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void* <tt class=                 "FUNCTION">                gnome_config_iterator_next</tt></code>(void* <tt                class="PARAMETER"><i>iterator_handle</i></tt>,                gchar** <tt class="PARAMETER"><i>key</i></tt>,                gchar** <tt class="PARAMETER"><i>                value</i></tt>);</code>              </p>            </div>            <p>              <b>Figure 6. Configuration file iterators</b>            </p>          </div>        </div>        <div class="SECT3">          <h3 class="SECT3">            <a name="Z85">Other Config File Operations</a>          </h3>          <p>            <a href="z79.html#STARTUP-GNOMECONFIGMISC">Figure 7</a>            lists some additional operations available for            manipulating config files. The most important of these            have already been mentioned in passing. <tt class=             "FUNCTION">gnome_config_sync()</tt> writes the            configuration file to disk, and <tt class="FUNCTION">            gnome_config_push_prefix()</tt> allows you to shorten            the path passed to the other <tt class="APPLICATION">            gnome-config</tt> functions. There are also boolean            tests, to ask <tt class="APPLICATION">gnome-config</tt>            whether a given section exists.          </p>          <p>            Two new operations are introduced: to <i class=             "FIRSTTERM">drop</i> a file or section means to forget            any information about it stored in memory, including            cached values loaded from the file and values not yet            saved to the file with <tt class="FUNCTION">            gnome_config_sync()</tt>. To <i class="FIRSTTERM">            clean</i> a file, section, or key means to unset its            value(s), so the file, section, or key will not exist            once <tt class="FUNCTION">gnome_config_sync()</tt> is            called.          </p>          <p>            <tt class="FUNCTION">gnome_config_sync()</tt>            automatically calls <tt class="FUNCTION">            gnome_config_drop_all()</tt> to free all <tt class=             "APPLICATION">gnome-config</tt> resources, since the            information is safely stored on disk.          </p>          <p>            Functions are also provided to get the "real"            (filesystem) path of a configuration file from a <tt            class="APPLICATION">gnome-config</tt> path. These are            unlikely to be useful in application code.          </p>          <div class="FIGURE">            <a name="STARTUP-GNOMECONFIGMISC"></a>            <div class="FUNCSYNOPSIS">              <a name="STARTUP-GNOMECONFIGMISC.SYNOPSIS"></a>              <table border="0" bgcolor="#E0E0E0" width="100%">                <tr>                  <td><pre class="FUNCSYNOPSISINFO">#include &lt;libgnome/gnome-config.h&gt;</pre>                  </td>                </tr>              </table>              <p>                <code><code class="FUNCDEF">gboolean <tt class=                 "FUNCTION">                gnome_config_has_section</tt></code>(const gchar*                <tt class="PARAMETER"><i>path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">gboolean <tt class=                 "FUNCTION">                gnome_config_private_has_section</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_drop_all</tt></code>(void);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_sync</tt></code>(void);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">gnome_config_sync_file</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_private_sync_file</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">gnome_config_drop_file</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_private_drop_file</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_clean_file</tt></code>(const gchar*                <tt class="PARAMETER"><i>path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_private_clean_file</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_clean_section</tt></code>(const gchar*                <tt class="PARAMETER"><i>path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_private_clean_section</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">gnome_config_clean_key</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_private_clean_key</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">gchar* <tt class=                 "FUNCTION">                gnome_config_get_real_path</tt></code>(const gchar*                <tt class="PARAMETER"><i>path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">gchar* <tt class=                 "FUNCTION">                gnome_config_private_get_real_path</tt></code>(const                gchar* <tt class="PARAMETER"><i>                path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_push_prefix</tt></code>(const gchar*                <tt class="PARAMETER"><i>path</i></tt>);</code>              </p>              <p>                <code><code class="FUNCDEF">void <tt class=                "FUNCTION">                gnome_config_pop_prefix</tt></code>(void);</code>              </p>            </div>            <p>              <b>Figure 7. Miscellaneous configuration file              functions</b>            </p>          </div>        </div>      </div>    </div>    <div class="NAVFOOTER">      <br>      <br>      <table width="100%" border="0" bgcolor="#ffffff" cellpadding=       "1" cellspacing="0">        <tr>          <td width="25%" bgcolor="#ffffff" align="left">            <a href="z77.html"><font color="#0000ff" size="2"><b>            &lt;&lt;&lt; Previous</b></font></a>          </td>          <td width="25%" colspan="2" bgcolor="#ffffff" align=           "center">            <font color="#0000ff" size="2"><b><a href="ggad.html">            <font color="#0000ff" size="2"><b>            Home</b></font></a></b></font>          </td>          <td width="25%" bgcolor="#ffffff" align="right">            <a href="sec-sessionmanagement.html"><font color=             "#0000ff" size="2"><b>Next &gt;&gt;&gt;</b></font></a>          </td>        </tr>        <tr>          <td colspan="2" align="left">            <font color="#000000" size="2"><b>Argument Parsing with            <tt class="APPLICATION">popt</tt></b></font>          </td>          <td colspan="2" align="right">            <font color="#000000" size="2"><b>Session            Management</b></font>          </td>        </tr>      </table>    </div>  </body></html>