smarty/docs/en/programmers/plugins/plugins-block-functions.xml

<?xml version="1.0" encoding="iso-8859-1"?>
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   <sect1 id="plugins.block.functions"><title>Block Functions</title>
    <funcsynopsis>
     <funcprototype>
      <funcdef>void <function>smarty_block_<replaceable>name</replaceable></function></funcdef>
      <paramdef>array <parameter>$params</parameter></paramdef>
      <paramdef>mixed <parameter>$content</parameter></paramdef>
      <paramdef>object <parameter>&amp;$smarty</parameter></paramdef>
      <paramdef>boolean <parameter>&amp;$repeat</parameter></paramdef>
     </funcprototype>
    </funcsynopsis>
    <para>
     Block functions are functions of the form:
     <literal>{func} .. {/func}</literal>. In other words, they enclose a
     template block and operate on the contents of
     this block. Block functions take precedence over
     <link linkend="language.custom.functions">custom functions</link> of
     the same name, that is, you cannot have both custom function
     <literal>{func}</literal> and block function
     <literal>{func}..{/func}</literal>.
    </para>

    <itemizedlist>
    <listitem><para>
     By default your function implementation is called twice by
     Smarty: once for the opening tag, and once for the closing tag.
     (See <literal>$repeat</literal> below on how to change this.)
    </para></listitem>
    <listitem><para>
     Only the opening tag of the block function may have
     <link linkend="language.syntax.attributes">attributes</link>. All
     attributes passed to template functions from the template are contained
     in the <parameter>$params</parameter> variable as an associative array.
     The opening tag attributes are also accessible to your function
     when processing the closing tag.
    </para></listitem>
    <listitem><para>
     The value of the <parameter>$content</parameter> variable depends on
     whether your function is called for the opening or closing tag. In case
     of the opening tag, it will be &null;, and in case of
     the closing tag it will be the contents of the template block.
     Note that the template block will have already been processed by
     Smarty, so all you will receive is the template output, not the
     template source.
    </para></listitem>

    <listitem><para>
     The parameter <parameter>$repeat</parameter> is passed by
     reference to the function implementation and provides a
     possibility for it to control how many times the block is
     displayed. By default <parameter>$repeat</parameter> is
     &true; at the first call of the block-function (the opening tag)
     and &false; on all subsequent calls to the block function
     (the block's closing tag).
     Each time the function implementation returns with
     <parameter>$repeat</parameter> being &true;, the contents between
     <literal>{func}...{/func}</literal> are evaluated and the function
     implementation is called again with the new block contents in the parameter
     <parameter>$content</parameter>.
	</para></listitem>
    </itemizedlist>

    <para>
     If you have nested block functions, it's possible to find out what the
     parent block function is by accessing
     <literal>$smarty->_tag_stack</literal> variable. Just do a
     <ulink url="&url.php-manual;var_dump"><varname>var_dump()</varname></ulink>
     on it and the structure should be apparent.
    </para>

    <example>
     <title>block function</title>
     <programlisting role="php">
<![CDATA[
<?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     block.translate.php
 * Type:     block
 * Name:     translate
 * Purpose:  translate a block of text
 * -------------------------------------------------------------
 */
function smarty_block_translate($params, $content, &$smarty, &$repeat)
{
    // only output on the closing tag
    if(!$repeat){
        if (isset($content)) {
            $lang = $params['lang'];
            // do some intelligent translation thing here with $content
            return $translation;
        }
    }
}
?>
]]>
     </programlisting>
    </example>

<para>
 See also:
 <link linkend="api.register.block"><varname>register_block()</varname></link>,
 <link linkend="api.unregister.block"><varname>unregister_block()</varname></link>.
</para>

   </sect1>

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