PhpRiot
News Archive
PhpRiot Newsletter
Your Email Address:

More information

Andrew Podner: Using Final to Prevent Overrides and Extension

Note: This article was originally published at PHPDeveloper on 27 November 2012.
PHPDeveloper

In the latest post to his site Andrew Podner takes a quick look at something you don't see too much in PHP applications but is a familiar concept to some coming in to the language from others - using "final" to prevent overrides of the code in your classes.

In a previous post about inheritance, I showed you how to extend a class. One aspect of extending classes that wasn't fully covered was the idea of overriding a method in a class. You can override a method (function) from the base class by simply redefining the method in the child class. [...] There are times though, when you do not want a method to ever be overridden. There may even be cases where you do not want a class to be extended.

His example shows how to use this "final" keyword on a database class, protecting a method (getRecord) that could potentially break the application if changed. This would then give the developer trying to extend the class an error noting that that method cannot be overridden. One thing to note, if you're going to use "final" in your code, be sure you know what you're doing. More often than not, you probably just want something like "private" or "protected" (see this post for a bit more explanation).