Programming PHP

Chapter 13. Application Techniques

By now, you should have a solid understanding of the details of the PHP language and its use in a variety of common situations. Now we’re going to show you some techniques that you may find useful in your PHP applications, such as code libraries, templating systems, efficient output handling, error handling, and performance tuning.

Code Libraries

As you’ve seen, PHP ships with numerous extension libraries that combine useful functionality into distinct packages that you can access from your scripts. In previous chapters, we’ve covered using the GD, pdflib, and Sablotron extension libraries, and Appendix B lists all of the available extensions.

In addition to using the extensions that ship with PHP, you can create libraries of your own code that you can use in more than one part of your web site. The general technique is to store a collection of related functions in a file, typically with a .inc file extension. Then, when you need to use that functionality in a page, you can use require_once( ) to insert the contents of the file into your current script.

For example, say you have a collection of functions that help create HTML form elements in valid HTML—one function creates a text field or a textarea (depending on how many characters you tell it the maximum is), another creates a series of pop-ups from which to set a date and time, and so on. Rather than copying the code into many pages, which is tedious, error-prone, and makes it difficult ...