TemplateMethod.com

====== Template Method Pattern ====== The [[Template Method]] is a [[Gang Of Four]] pattern which could also be described as the frameworkers pattern: essentially it's an application of polymorphism. The general approach of the template method is to define a set of general class methods which subclasses can (perhaps optionally) override the template method with a different implementation. This then allows either the superclass or some other class to be given any object containing the template method(s) and execute it, producing varying output. ===== Example =====




TemplateMethod.com


EOD;
        return $html;
   }
   // Template method
   function footer() {
       $html = <<© TemplateMethod Inc. 2003


EOD;
        return $html;
   }
   // Template method
   function body() {
       // Do nothing
   }
}

class Login extends Page {
   // Template method
   function body() {
       $html = <<






EOD;
       return $html;
   }
}

class News extends Page {
   // Template method
   function header() {
       $html = <<

TemplateMethod.com - Latest News


EOD;
        return $html;
   }

   // Template method
   function body() {
        $html = <<Latest News

EOD;
        return $html;
   }
}

class PageWriter {
    var $page;
    function PageWriter($page) {
        $this->page = $page;
    }
    function render() {
        $html = $this->page->header();
        $html .= $this->page->body();
        $html .= $this->page->footer();
        return $html;
    }
}

switch ( strtolower(@$_GET['page']) ) {
    case 'login':
        $page = new Login();
    break;
    case 'news':
        $page = new News();
    break;
    default:
        trigger_error('Invalid page',E_USER_ERROR);
    break;
}

$pageWriter = new PageWriter($page);
echo ( $pageWriter->render() );
?>

===== WACT implementation ===== The [[Template Method]] is used extensively in the WACT [[wact:Template Component Architecture]], allowing customizable tag components to be defined at compile time, which write specific code into the compiled template. ===== Additional Information ===== * WACT [[wact:Template Component Architecture]] * [[http://jamesthornton.com/eckel/TIPython/html/Sect04.htm|Bruce Eckel in Thinking in Python]] - demonstrates the framework concept with a [[Template Method]] * [[http://www.zend.com/zend/php5/php5-OOP.php|The Template Method Pattern in PHP 5]]