<?php
//copyright Lawrence Truett and FluffyCat.com 2006, all rights reserved

  include_once('Book.php');  
  
  abstract class TemplateAbstract {
    
    //the template method 
    //  sets up a general algorithm for the whole class 
    public final function showBookTitleInfo($book_in) {
      $title = $book_in->getTitle();
      $author = $book_in->getAuthor();
      $processedTitle = $this->processTitle($title);
      $processedAuthor = $this->processAuthor($author);
      if (NULL == $processedAuthor) {
        $processed_info = $processedTitle;
      } else {
        $processed_info = $processedTitle.' by '.$processedAuthor;
      }
      return $processed_info;
    }
    
    //the primitive operation
    //  this function must be overridded
    abstract function processTitle($title);
    
    //the hook operation
    //  this function may be overridden, 
    //  but does nothing if it is not
    function processAuthor($author) {
      return NULL;
    } 
    
  }
?>