Where to Go After the Navigator

We developed these database classes because they are useful in themselves, but they also show the versatility of the PageNavigator class—this is not a one trick pony but a class that can be reused in a variety of situations. Along the way, you've also learned more about OOP and the process of class creation. This is not something that takes place in a vacuum. Knowledge of existing PHP functions and of SQL was essential to the process and conditioned the result. What you already know about PHP as a procedural programmer and about SQL has proven to be an invaluable asset.

In the next chapter we'll improve on the database classes introduced here and explore one of the most important concepts of OOP, inheritance. We'll also look at one of the classes built in to PHP 5, namely Exception. From now on we will make use of classes built in to PHP 5 so code compatible with PHP 4 can no longer be provided.