xforms

    the ``truth'' of a particular value. (A given string is true if

    it is nonempty.) For a full list of the comparison operators

    available to you, see the <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>

    documentation.</p>

    documentation. Here are some examples of how one might use this

    construct.</p>

    <p>For example, if you wish to customize the text on your web page

    based on the time of day, you could use the following recipe, placed

    in the HTML page:</p>

    <p>In your configuration file, you could put the following

    line:</p>

<div class="example"><p><code>

        BrowserMatchNoCase macintosh Mac<br />

        BrowserMatchNoCase MSIE InternetExplorer

</code></p></div>

    <p>This will set environment variables ``Mac'' and

    ``InternetExplorer'' to true, if the client is running Internet

    Explorer on a Macintosh.</p>

    <p>Then, in your SSI-enabled document, you might do the

    following:</p>

<div class="example"><p><code>

    Good

    &lt;!--#if expr="%{TIME_HOUR} &gt;=12" --&gt;<br />

    morning!<br />

        &lt;!--#if expr="${Mac} &amp;&amp; ${InternetExplorer}" --&gt;<br />

        Apologetic text goes here<br />

        &lt;!--#else --&gt;<br />

    afternoon!<br />

    &lt;!--#endif --&gt;<br />

        Cool JavaScript code goes here<br />

        <!--#endif -->

</code></p></div>

    <p>Not that I have anything against IE on Macs - I just

    struggled for a few hours last week trying to get some

    JavaScript working on IE on a Mac, when it was working

    everywhere else. The above was the interim workaround.</p>

    <p>Any other variable (either ones that you define, or normal

    environment variables) can be used in conditional statements.

    See <a href="../expr.html">Expressions in Apache HTTP Server</a> for

    more information on the expression evaluation engine.</p>

    <p>With Apache's ability to set environment variables with the

    With Apache's ability to set environment variables with the

    <code>SetEnvIf</code> directives, and other related directives,

    this functionality can let you do a wide variety of dynamic content

    on the server side without resorting a full web application.</p>

    this functionality can let you do some pretty involved dynamic

    stuff without ever resorting to CGI.</p>

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