Page 255 - Beginning PHP 5.3

Chapter 8: Objects
Summary

This chapter explored the large and wonderful world of object - oriented programming in PHP. You
learned some of the benefits of an object - oriented approach, and explored the following OOP topics:
❑ The basic building blocks of OOP: classes, objects, properties, and methods
❑ Creating classes and objects in PHP. You learned about property and method visibility, and how
to create and access properties and methods. Along the way, you studied static properties
and methods; class constants; parameters and return values; how to access properties from
within methods; and how to use hints to check the class of objects passed to methods and
functions
❑ The concept of encapsulation — the idea that objects should be as self - contained as possible —
and how to put this into practice when creating your own classes
❑ Three special methods that you can use to overload objects: __get() , __set() , and __call() .
You learned how to use these methods to intercept property accesses and method calls,
letting you create very powerful, flexible classes
❑ Inheritance, one of the most important and powerful aspects of OOP. You learned how to create
child classes; how to override methods in a parent class; how to access parent methods; how to
prevent inheritance with the final keyword; and how to use abstract classes and interfaces
to add consistency to your classes, making them more readily adaptable and extendable for
yourself and for other developers
❑ How to use constructors and destructors to initialize and clean up your objects
❑ Using PHP ’ s __autoload() function to automatically retrieve class files on the fly
❑ Converting objects to strings — and back again — using PHP ’ s handy serialize() and
unserialize() functions
❑ How to find out the class of an object using get_class() and instanceof
Though this chapter has given you enough knowledge to write fully fledged object - oriented
applications, there is yet more to learn about object - oriented programming in PHP, including reflection,
late static binding, and object cloning. To read about these more advanced topics, take a look at the
“ Classes and Objects ” section of the PHP Language Reference at http://www.php.net/manual/en/
langref.php . You might also like to try the exercises at the end of this chapter to put your OOP skills to
work. You can find the solutions to these exercises in Appendix A.

You have now learned the basic concepts of the PHP language. In the third and final part of the book you
put all this theory into practice, and learn techniques for building real - world PHP Web applications. The
next chapter gets the ball rolling with a look at creating and processing Web forms, which are often used
extensively throughout interactive Web sites.

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