Introduction

It’s quite probable that during your life as a PHP developer, you have found yourself updating specific modules of a given web application (or in the worst case, the entire application), since the context where it was originally conceived to work has changed noticeably.

Naturally, if this situation sounds familiar to you, then you’ll know that updating certain parts of an application can be an annoying, time-consuming process. it can be even worse if you have to deal with other issues apart from the ones related to coding, such as suiting deadlines, solving “creative” differences between members of the same development team, and so forth.

Thus, considering all the possible problems that can emerge when a particular PHP application must be updated, you try to write code that is highly maintainable and easy to update. However, if I translate the aforementioned scenario to the terrain of object-oriented programming, sometimes it happens that one or more PHP classes need to be updated according to the modifications introduced into the context where they were initially designed to work.

From a developer’s point of view, this updating process can be difficult, particularly if the application that needs to be modified is comprised of a considerable number of interrelated classes. Therefore, the question that comes up here is: is there any programmatic mechanism that allows you to create a class that changes the way it works, according to the variations incorporated into its environment?

Fortunately, the answer to the previous question is an emphatic yes! In the huge area of pattern-based programming, there’s one pattern called “Stage” that provides developers with a handy mechanism for building a class that’s capable of modifying its behavior in response to the changes introduced into its environment. Indeed, this sounds pretty interesting, right?

Nevertheless, at least at first glance, the definition of the “Stage” pattern seems hard to grasp, which implies that the pattern in question has to be addressed from a practical point of view. In doing so, you’ll have a much better idea of how it works, and eventually how it can be applied in concrete cases.

Therefore, assuming that the stage pattern has already caught your attention, over the course of this two-part series, I’m going to introduce its key concepts, and logically show you how to implement it with copious code samples.

At the end of this series, you should be equipped with a decent background in how to include the stage pattern in your own PHP applications, aside from expanding your overall skills in pattern-based programming. So, are you ready to dive deeper into the implementation of this handy pattern? Let’s begin now!