repo_zf1/documentation/manual/en/module_specs/Zend_Layout-Advanced.xml

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<sect1 id="zend.layout.advanced">
    <title>Zend_Layout Advanced Usage</title>

    <para>
        <classname>Zend_Layout</classname> has a number of use cases for the advanced
        developer who wishes to adapt it for different view implementations,
        file system layouts, and more.
    </para>

    <para>
        The major points of extension are:
    </para>

    <itemizedlist>
        <listitem>
            <para>
                <emphasis>Custom view objects.</emphasis>
                <classname>Zend_Layout</classname> allows you to utilize any class that
                implements <classname>Zend_View_Interface</classname>.
            </para>
        </listitem>

        <listitem>
            <para>
                <emphasis>Custom front controller plugins.</emphasis>
                <classname>Zend_Layout</classname> ships with a standard front controller
                plugin that automates rendering of layouts prior to returning
                the response. You can substitute your own plugin.
            </para>
        </listitem>

        <listitem>
            <para>
                <emphasis>Custom action helpers.</emphasis>
                <classname>Zend_Layout</classname> ships with a standard action helper
                that should be suitable for most needs as it is a dumb proxy
                to the layout object itself.
            </para>
        </listitem>

        <listitem>
            <para>
                <emphasis>Custom layout script path resolution</emphasis>.
                <classname>Zend_Layout</classname> allows you to use your own <link
                    linkend="zend.filter.inflector">inflector</link> for layout
                script path resolution, or simply to modify the attached
                inflector to specify your own inflection rules.
            </para>
        </listitem>
    </itemizedlist>

    <sect2 id="zend.layout.advanced.view">
        <title>Custom View Objects</title>

        <para>
            <classname>Zend_Layout</classname> allows you to use any class implementing
            <classname>Zend_View_Interface</classname> or extending
            <classname>Zend_View_Abstract</classname> for rendering your layout script.
            Simply pass in your custom view object as a parameter to the
            constructor/<methodname>startMvc()</methodname>, or set it using the
            <methodname>setView()</methodname> accessor:
        </para>

        <programlisting language="php"><![CDATA[
$view = new My_Custom_View();
$layout->setView($view);
]]></programlisting>

        <note>
            <title>Not all Zend_View implementations are equal</title>

            <para>
                While <classname>Zend_Layout</classname> allows you to use any class
                implementing <classname>Zend_View_Interface</classname>, you may run into
                issues if they can not utilize the various
                <classname>Zend_View</classname> helpers, particularly the layout and
                <link linkend="zend.view.helpers.initial.placeholder">placeholder</link>
                helpers. This is because <classname>Zend_Layout</classname> makes
                variables set in the object available via itself and
                <link linkend="zend.view.helpers.initial.placeholder">placeholders</link>.
            </para>

            <para>
                If you need to use a custom <classname>Zend_View</classname>
                implementation that does not support these helpers, you will
                need to find a way to get the layout variables to the view. This
                can be done by either extending the <classname>Zend_Layout</classname>
                object and altering the <methodname>render()</methodname> method to pass
                variables to the view, or creating your own plugin class that
                passes them prior to rendering the layout.
            </para>

            <para>
                Alternately, if your view implementation supports any sort of plugin capability, you
                can access the variables via the 'Zend_Layout' placeholder, using the <link
                    linkend="zend.view.helpers.initial.placeholder">placeholder helper</link>:
            </para>

            <programlisting language="php"><![CDATA[
$placeholders = new Zend_View_Helper_Placeholder();
$layoutVars   = $placeholders->placeholder('Zend_Layout')->getArrayCopy();
]]></programlisting>
        </note>
    </sect2>

    <sect2 id="zend.layout.advanced.plugin">
        <title>Custom Front Controller Plugins</title>

        <para>
            When used with the <acronym>MVC</acronym> components, <classname>Zend_Layout</classname>
            registers a front controller plugin that renders the layout as the
            last action prior to exiting the dispatch loop. In most cases, the
            default plugin will be suitable, but should you desire to write
            your own, you can specify the name of the plugin class to load by
            passing the <property>pluginClass</property> option to the
            <methodname>startMvc()</methodname> method.
        </para>

        <para>
            Any plugin class you write for this purpose will need to extend
            <classname>Zend_Controller_Plugin_Abstract</classname>, and should accept a
            layout object instance as an argument to the constructor. Otherwise,
            the details of your implementation are up to you.
        </para>

        <para>
            The default plugin class used is
            <classname>Zend_Layout_Controller_Plugin_Layout</classname>.
        </para>
    </sect2>

    <sect2 id="zend.layout.advanced.helper">
        <title>Custom Action Helpers</title>

        <para>
            When used with the <acronym>MVC</acronym> components, <classname>Zend_Layout</classname>
            registers an action controller helper with the helper broker. The
            default helper,
            <classname>Zend_Layout_Controller_Action_Helper_Layout</classname>, acts as a
            dumb proxy to the layout object instance itself, and should be
            suitable for most use cases.
        </para>

        <para>
            Should you feel the need to write custom functionality, simply write
            an action helper class extending
            <classname>Zend_Controller_Action_Helper_Abstract</classname> and pass the
            class name as the <property>helperClass</property> option to the
            <methodname>startMvc()</methodname> method. Details of the implementation are
            up to you.
        </para>
    </sect2>

    <sect2 id="zend.layout.advanced.inflector">
        <title>Custom Layout Script Path Resolution: Using the Inflector</title>

        <para>
            <classname>Zend_Layout</classname> uses <classname>Zend_Filter_Inflector</classname> to
            establish a filter chain for translating a layout name to a layout
            script path. By default, it uses the rules 'Word_CamelCaseToDash'
            followed by 'StringToLower', and the suffix 'phtml' to transform the
            name to a path. As some examples:
        </para>

        <itemizedlist>
            <listitem>
                <para>'foo' will be transformed to 'foo.phtml'.</para>
            </listitem>

            <listitem>
                <para>'FooBarBaz' will be transformed to 'foo-bar-baz.phtml'.</para>
            </listitem>
        </itemizedlist>

        <para>
            You have three options for modifying inflection: modify the
            inflection target and/or view suffix via <classname>Zend_Layout</classname>
            accessors, modify the inflector rules and target of the inflector
            associated with the <classname>Zend_Layout</classname> instance, or create
            your own inflector instance and pass it to
            <methodname>Zend_Layout::setInflector()</methodname>.
        </para>

        <example id="zend.layout.advanced.inflector.accessors">
            <title>Using Zend_Layout accessors to modify the inflector</title>

            <para>
                The default <classname>Zend_Layout</classname> inflector uses static
                references for the target and view script suffix, and
                has accessors for setting these values.
            </para>

            <programlisting language="php"><![CDATA[
// Set the inflector target:
$layout->setInflectorTarget('layouts/:script.:suffix');

// Set the layout view script suffix:
$layout->setViewSuffix('php');
]]></programlisting>
        </example>

        <example id="zend.layout.advanced.inflector.directmodification">
            <title>Direct modification of Zend_Layout inflector</title>

            <para>
                Inflectors have a target and one or more rules. The default
                target used with <classname>Zend_Layout</classname> is ':script.:suffix';
                ':script' is passed the registered layout name, while ':suffix'
                is a static rule of the inflector.
            </para>

            <para>
                Let's say you want the layout script to end in the suffix
                'html', and that you want to separate MixedCase and camelCased words with
                underscores instead of dashes, and not lowercase the name.
                Additionally, you want it to look in a 'layouts' subdirectory
                for the script.
            </para>

            <programlisting language="php"><![CDATA[
$layout->getInflector()->setTarget('layouts/:script.:suffix')
                       ->setStaticRule('suffix', 'html')
                       ->setFilterRule(array('Word_CamelCaseToUnderscore'));
]]></programlisting>
        </example>

        <example id="zend.layout.advanced.inflector.custom">
            <title>Custom inflectors</title>

            <para>
                In most cases, modifying the existing inflector will be enough.
                However, you may have an inflector you wish to use in several
                places, with different objects of different types.
                <classname>Zend_Layout</classname> supports this.
            </para>

            <programlisting language="php"><![CDATA[
$inflector = new Zend_Filter_Inflector('layouts/:script.:suffix');
$inflector->addRules(array(
    ':script' => array('Word_CamelCaseToUnderscore'),
    'suffix'  => 'html'
));
$layout->setInflector($inflector);
]]></programlisting>
        </example>

        <note>
            <title>Inflection can be disabled</title>

            <para>
                Inflection can be disabled and enabled using accessors on the
                <classname>Zend_Layout</classname> object. This can be useful if you want
                to specify an absolute path for a layout view script, or know
                that the mechanism you will be using for specifying the layout
                script does not need inflection. Simply use the
                <methodname>enableInflector()</methodname> and
                <methodname>disableInflector()</methodname> methods.
            </para>
        </note>
    </sect2>
</sect1>
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