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copied!<h2>About object inheritance</h2> <p>A class is a template for objects, and defines object properties and methods, while object is instance of a class. When you extend a class, the child class inherits properties and methods from a parent.</p> <p>In your case, there is no inheritance (parent-child relationship), <code>$_header</code> as a separate object is only property of a <code>$_page</code>. To enable a ‘communication’ between those two objects, <code>$_header</code> must have a reference to a <code>$_page</code> object.</p> <hr> <h2>Template class</h2> <p>This is a modified version of the Template class you are using. When you dynamically create properties, <code>__set()</code> and <code>__get()</code> <a href="http://php.net/manual/en/language.oop5.magic.php" rel="nofollow">magic methods</a> should be used. It also uses <code>__toString()</code> method, so that the template objects can be treated as a string. All variables that template file uses, should be assigned to template object. By using a class defined like this, all templates are rendered simultaneously.</p> <pre><code>class tplEngine { private $template = ''; public function __set( $var, $content ) { $this->$var = $content; } public function __get( $var ) { return ( isset($this->$var) ? $this->$var : null ); } public function __construct( $template ) { // is_readable() - tells whether a file exists and is readable if ( !is_readable( $template ) ) throw new IOException( "Could not find or access file: $template" ); $this->template = $template; } public function __toString() { ob_start(); require ( $this->template ); $content = ob_get_clean(); return $content; } } // usage: $_page = new tplEngine( TPLFILES_DIR . "/root.php" ); $_header = new tplEngine( TPLFILES_DIR . "/common/header.html" ); $_header->isLoggedIn = true; $_header->username = 'some-username'; $_page->header = $_header; // in root.php echo $this->header; </code></pre> <hr> <h2>Accessing parent variables</h2> <p><strong>Parent property</strong></p> <p>One way to access variables in 'parent' object is to add parent property to template class through constructor:</p> <pre><code>public function __construct( $template, $parent = null ) { // is_readable() - tells whether a file exists and is readable if ( !is_readable( $template ) ) throw new IOException( "Could not find or access file: $template" ); $this->template = $template; $this->_parent = $parent; } </code></pre> <p>Access parent properties in templates like:</p> <pre><code>$this->_parent->username; </code></pre> <p><strong>Make parent properties local</strong></p> <p>Another way is to make them local ( neat trick if you don’t want to bother with the <code>$this->_parent</code> calls ):</p> <pre><code>public function __toString() { ob_start(); if ( $this->_parent ) { foreach ( get_object_vars( $this->_parent ) as $key => $value ) $$key = $value; } require ( $this->template ); $content = ob_get_clean(); return $content; } </code></pre> <h2>Additional info</h2> <p><a href="http://sourcemaking.com/design_patterns/adapter/php" rel="nofollow">Adapter Design Pattern</a></p> <p><a href="http://www.php.net/manual/en/language.oop5.overloading.php" rel="nofollow">PHP Overloading</a></p> <p><a href="http://php.net/manual/en/language.oop5.magic.php" rel="nofollow">Magic Methods</a></p> <p><a href="http://www.smarty.net/docs/en/language.variable.scopes.tpl" rel="nofollow">Smarty Template Engine - variable scopes</a> </p>

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