php html template class system

PHP

/* custom html template class v0.1 

html templates are located in /templates/

usage example:

$page = new template("page.html");
$page->set("title", "HTML Ipsum Example - generated from page.html template");
$page->set("class", "page-class");
$page->set("content", ipsum_kitchen_sink());
return $page_content = $page->output();

*/

class template {
    public $file;
    public $dir = "templates/";
    public $values = array();
  
    public function __construct($file) {
        $this->file = $file;
    }

	public function set($key, $value) {
	    $this->values[$key] = $value;
	}
	  
	public function output() {
	    if (!file_exists($this->dir . $this->file)) {
	        return "Error loading template file ($this->dir . $this->file).";
	    }
	    $output = file_get_contents($this->dir . $this->file);
	  
	    foreach ($this->values as $key => $value) {
	        $tagToReplace = "[@$key]";
	        $output = str_replace($tagToReplace, $value, $output);
	    }
	  
	    return $output;
	}

}

$card = new template("card.html");
$card->set("title", "HTML Ipsum Example - generated from page.html template");
$card->set("class", "page-class");
$card->set("content", ipsum_kitchen_sink());
// return $page_content = $page->output();
echo $card->output();