Learning PHP, MySQL, JavaScript, and CSS, 2nd Edition

PHP Objects

In much the same way that functions represent a huge increase in programming power over the early days of computing, where sometimes the best program navigation available was a very basic GOTO or GOSUB statement, object-oriented programming (OOP) takes the use of functions to a whole new level.

Once you get the hang of condensing reusable bits of code into functions, it’s not that great a leap to consider bundling the functions and their data into objects.

Let’s consider a social networking site that has many parts. One handles all user functions: code to enable new users to sign up and to enable existing users to modify their details. In standard PHP, you might create a few functions to handle this and embed some calls to the MySQL database to keep track of all the users.

Imagine how much easier it would be, though, to create an object to represent the current user. To do this you could create a class, perhaps called User, which would contain all the code required for handling users and all the variables needed for manipulating the data within the class. Then, whenever you needed to manipulate a user’s data, you could simply create a new object with the User class.

You could treat this new object as if it were the actual user. For example, you could pass the object a name, password, and email address; ask it whether such a user already exists; and, if not, have it create a new user with those attributes. You could even have an instant messaging object, or one for managing ...