Errors are a fact of life; that's as true in programming as anywhere else. Building a program that can handle user errors gracefully is essential. This five-part series will show you how. It's exceprted from chapter eight of the book Beginning PHP and PostgreSQL 8: From Novice to Professional, written by W. Jason Gilmore and Robert H. Treat (Apress; ISBN: 1590595475).
Even if you wear an S on your chest when it comes to programming, you can be sure that errors will be a part of all but the most trivial of applications. Some of these errors are programmer-induced; that is, they’re the result of blunders during the development process. Others are user-induced, caused by the end user’s unwillingness or inability to conform to application constraints. For example, the user might enter “12341234” when asked for an e-mail address, obviously ignoring what would otherwise be expected as valid input. Regardless of the source of the error, your application must be able to encounter and react to such unexpected errors in a graceful fashion, hopefully doing so without a loss of data or the crash of a program or system. In addition, your application should be able to provide users with the feedback necessary to understand the reason for such errors and potentially adjust their behavior accordingly.
This chapter introduces several features PHP has to offer for handling errors. Specifically, the following topics are covered:
Configuration directives: PHP’s error-related configuration directives determine the bulk of the language’s error-handling behavior. Many of the most pertinent directives are introduced in this chapter.
Error logging: Keeping a running log of application errors is the best way to record progress regarding the correction of repeated errors, as well as quickly take note of newly introduced problems. In this chapter, you learn how to log messages to both your operating system syslog and a custom log file.
Exception handling: This long-awaited feature, prevalent among many popular languages (Java, C#, and Python, to name a few) and new to PHP 5, offers a standardized process for detecting, responding to, and reporting errors.
Historically, the development community has been notoriously lax in implementing proper application error handling. However, as applications continue to grow increasingly complex and unwieldy, the importance of incorporating proper error-handling strategies into your daily development routine cannot be understated. Therefore, you should invest some time becoming familiar with the many features PHP has to offer in this regard.
