Summary

With limited space available, it has not been possible to cover everything. There are two directions to take in further research: One should yield breadth and the other depth. By breadth, I mean the features that were beyond the scope of this article, such as abstract classes, interfaces, the iterator interface, reflection, exceptions, and object cloning. By depth, I mean questions of design. While it is important to understand the range of tools available in PHP for object-oriented programming, it is equally crucial to consider how best to work with such features. Fortunately, there are many resources available that focus on patterns of design in an object-oriented context (see Resources).

If you are still programming with PHP V4, I hope you found enough new features to justify migrating to V5 and its core object-oriented features. You'll soon wonder how you managed without them.

Resources

• The essential overview of all PHP's object-oriented features classes and objects (PHP V5) can be found in Chapter 19 of the official PHP Manual.
  
  
• For an article that expands on issues of type with reference to abstract classes, see Working with Class Types: Abstract Classes and Interfaces.
  
  
• For an overview of error handling with PHP V5, see Exceptional Code.
  
  
• For a fantastic resource for anyone interested in object-oriented design, visit C2 Wiki.
  
  
• The home page of the PHP language and the place to download PHP is PHP.net.
  
  
• PHP Builder is popular PHP site with tutorials and code libraries.
  
  
• Zend.com contains plenty of useful links and information about PHP. Zend is the PHP Optimizer.
  
  
• Find complete listings of the articles, tutorials, project info, and news you need to stay up to date on developing with PHP at developerWorks PHP top projects.
  
  
• Visit the developerWorks Open source zone for extensive how-to information, tools, and project updates to help you develop with open source technologies and use them with IBM's products.
  
  
• Innovate your next open source development project with IBM trial software, available for download or on DVD.
  
  
• Find hundreds of discounted books on open source topics in the Open source section of The Developer Bookstore, including many books on PHP.
  
  
• Get involved in the developerWorks community by participating in developerWorks blogs.