Beginning PHP 5.3

Chapter 20. Writing High-Quality Code

If you've worked your way through the book thus far, you have a good grounding in the techniques needed to write complex PHP Web applications. Congratulations! Before concluding the book, however, it's worth taking a look at how to write high-quality applications. The term "high-quality" is somewhat subjective, but for the purposes of this book it means code that:

• Is easy to read, maintain, and extend

• Is secure — that is, protected from attacks

• Handles error conditions and problems in a robust and graceful way

• Is well tested

As your Web applications grow larger and more complex, the quality of your code becomes more and more important. A large code base can quickly become error-prone and difficult to work with if strict quality standards aren't maintained. In this chapter you learn the following quality-control techniques:

• Splitting your code into manageable, reusable chunks

• Using a set of coding standards to keep your code easy to read

• Writing documentation to improve readability for other programmers who work on your code

• Validating input, as well as encoding output, to mitigate the risk of security holes in your code

• Dealing with error conditions — that is, handling abnormal situations while your code is running

• Cleanly separating your application's business logic from its user interface

• Using automated testing frameworks to improve the quality of your code

By the end of this chapter you'll have the know-how to create PHP applications that are robust, ...