gistfile1.php

/**
    * retrieves rendered field template
    * @param string $templateName
    * @param function $prepareTemplateDataFunction a method that accepts 1 param the template data array object and returns it modified before passing it to the template for rendering
    * @return string
    */
   public function render($templateName, callable $prepareTemplateDataFunction = null){
      $template = $this->getTemplate($templateName);

      $templateData = $this->getTemplateData();
      
       if($prepareTemplateDataFunction){
           $templateData = $prepareTemplateDataFunction($templateData);
       }
       
       $template->templateData = $templateData;
       
       return $template->fetch();
   }