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<h1>Templates: Part II</h1>

<a name="dct"></a>
<h2>Dynamic Content Tags</h2>
<p>
Dynamic content tags are introduced as shortcuts to some commonly used <a href="?page=Configurations.Templates1#ct">component tags</a>. These tags are mainly used to render contents resulted from evaluating some PHP expressions or statements. They include <a href="#et">expression tags</a>, <a href="#st">statement tags</a>, <a href="#dt">databind tags</a>, <a href="#pt">parameter tags</a>, <a href="#at">asset tags</a> and <a href="#lot">localization tags</a>.
</p>

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<h3>Expression Tags</h3>
<p>
An expression tag represents a PHP expression that is evaluated when the template control is in <tt>PreRender</tt> stage. The expression evaluation result is inserted at the place where the tag resides in the template. The context (namely <tt>$this</tt>) of the expression is the control owning the template.
</p>
<p>
The format of an expression tag is as follows,
</p>
<com:TTextHighlighter Language="prado" CssClass="source">
&lt;%= PhpExpression %&gt;
</com:TTextHighlighter>
<p>
For example, the following expression tag will display the current page title at the place,
</p>
<com:TTextHighlighter Language="prado" CssClass="source">
&lt;%= $this-&gt;Title %&gt;
</com:TTextHighlighter>

<a name="st"></a>
<h3>Statement Tags</h3>
<p>
Statement tags are similar to expression tags, except that statement tags contain PHP statements rather than expressions. The output of the PHP statements (using for example <tt>echo</tt> or <tt>print</tt> in PHP) are displayed at the place where the statement tag resides in the template. The context (namely <tt>$this</tt>) of the statements is the control owning the template. The format of statement tags is as follows,
</p>
<com:TTextHighlighter Language="prado" CssClass="source">
&lt;%%
PHP Statements
%&gt;
</com:TTextHighlighter>
<p>
The following example displays the current time in Dutch at the place,
</p>
<com:TTextHighlighter Language="prado" CssClass="source">
&lt;%%
setlocale(LC_ALL, 'nl_NL');
echo strftime("%A %e %B %Y",time());
%&gt;
</com:TTextHighlighter>

<a name="dt"></a>
<h3>Databind Tags</h3>
<p>
Databind tags are similar to expression tags, except that the expressions are evaluated only when a <tt>dataBind()</tt> call is invoked on the controls representing the databind tags. The context (namely <tt>$this</tt>) of a databind expression is the control owning the template. The format of databind tags is as follows,
</p>
<com:TTextHighlighter Language="prado" CssClass="source">
&lt;%# PhpExpression %&gt;
</com:TTextHighlighter>

<a name="pt"></a>
<h3>Parameter Tags</h3>
<p>
Parameter tags are used to insert application parameters at the place where they appear in the template. The format of parameter tags is as follows,
</p>
<com:TTextHighlighter Language="prado" CssClass="source">
&lt;%$ ParameterName %&gt;
</com:TTextHighlighter>
<p>
Note, application parameters are usually defined in application configurations or page directory configurations. The parameters are evaluated when the template is instantiated.
</p>

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<h3>Asset Tags</h3>
<p>
Asset tags are used to publish private files and display the corresponding the URLs. For example, if you have an image file that is not Web-accessible and you want to make it visible to end-users, you can use asset tags to publish this file and show the URL to end-users so that they can fetch the published image.
</p>
<p>
The format of asset tags is as follows,
</p>
<com:TTextHighlighter Language="prado" CssClass="source">
&lt;%~ LocalFileName %&gt;
</com:TTextHighlighter>
<p>
where <tt>LocalFileName</tt> refers to a file path that is relative to the directory containing the current template file. The file path can be a single file or a directory. If the latter, the content in the whole directory will be made accessible by end-users.
</p>
<p>
BE VERY CAUTIOUS when you are using asset tags as it may expose to end-users files that you probably do not want them to see.
</p>

<a name="lot"></a>
<h3>Localization Tags</h3>
<p>
Localization tags represent localized texts. They are in the following format,
</p>
<com:TTextHighlighter Language="prado" CssClass="source">
&lt;%[string]%&gt;
</com:TTextHighlighter>
<p>
where <tt>string</tt> will be translated to different languages according to the end-user's language preference. Localization tags are in fact shortcuts to the function call <tt>Prado::localize(string)</tt>.
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