Design patterns are just for Java architects — at least that's what you may have always thought. In fact, design patterns are useful for everyone. If these tools are not the preserve of “architectural astronauts,” then what are they? Why are they useful in PHP applications? This article explains these issues.

Design Patterns introduced design patterns to the software community with the book Design Patterns, written by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides Design (commonly known as the "Gang of Four"). The core concepts behind the design patterns presented are very simple. After years of practicing software development, Gamma and others have discovered certain patterns with fixed designs, much like architects design houses and buildings, developing templates for where a bathroom should be or how a kitchen should be constructed. Using these templates, or design patterns, means designing better buildings faster. The same concept applies to software.

Design patterns not only represent a useful way to develop robust software faster, but they also provide a way to encapsulate large ideas in friendly terms. For example, you could say that you are writing a messaging system that provides loose coupling, or you could say that you are writing a pattern named Observer.

Demonstrating the value of patterns with smaller examples is very difficult. This often feels like overkill, since patterns actually work in large code bases. This article does not demonstrate a large application, so you need to think about ways to apply the principles of the example in your own large application—not the code itself demonstrated in this article. This is not to say that you shouldn't use patterns in small applications. Many good applications start out as small applications and progress to large applications, so there's no reason not to build on these types of solid coding practices.