PHP 5 in Practice

7. Classes and Objects Before delving into object-oriented programming in PHP, you must first note that PHP 5 has seen a complete rewrite of its object-oriented capabilities. Because a full discussion of object-oriented programming (OOP) is ...

7.1. Automatically Loading Class Source Files It is a common OOP practice to place each of your class definitions into separate files. Even if this is not done, it is a good practice to group various class definitions into multiple files based on ...

7.2. Protecting Object Data (public/private/protected) PHP 5 includes a full object model that, like other object-oriented languages, allows for visibility permissions to be set on variables and methods. The keywords for doing this and their defin...

7.3. Automatically Running Code On Creation or Destruction of an Object There are times when you want to automatically have certain code run when a new instantiation of an object is created. This might be used to automatically fill data elements...

7.4. Accessing a Class's Members Without Instantiation Sometimes you may want to create a class but have its methods or variables accessible without creating a new instantiation of the class. To allow for this, you need to declare any variable you...

7.5. Extending a Class Definition Inheritance, a core concept of object-oriented design, is the idea that one class may be the child, or extension, of another class. In this case the child inherits all properties of the parent, and yet at the same...

7.6. Creating an Abstract Class As the previous section demonstrated, extending classes can be a powerful tool. However, there may be times you want to create a class that must be extended to use it. Abstract classes are just this. In declaring a ...

7.7. Using Object Interfaces Abstract classes as just described are powerful ways to define how new classes are constructed. Sometimes, however, you don't want to fully define a class. Instead you need to specify that classes must implement a cert...

7.8. Dynamic and Overloaded Variable Names PHP 5 allows you to dynamically accept any variable name accessed within an object. By defining the __set() and __get() methods, you can tell the object how to handle any variable names that it did not ...

7.9. Overloading Methods PHP, like most object-oriented languages, supports the idea of overloading methods. Overloading is simply the ability to define multiple functions that have the same name but differ in the type or number of parameters th...

7.10. Linked List Implementation Linked lists are one of the basic data structures found in computer programming and are often the basis of more complicated data structures. The features of a linked list are that new elements can be added and re...

7.11. Binary Tree Implementation The binary tree and its many variants are the mainstays of the data structure family. A variation of the linked list, binary trees excel in situations where data must be quickly organized and quickly retrieved in a...