Check for Function and Class Existence Using PHP
When you've inherited a big website or you're working on a group website where you don't have quick access to communicate with the other developers, it's important to not assume that a custom function or class name has not already been defined. Here's how you can protect yourself:
The PHP
if(!function_exists('show_article')) {
function show_article($id) {
//code here
}
}
if(!class_exists('my_class')) {
class myclass {
//code here
}
}
Using this type of programming can also protect you in case a file gets accidentally included twice. If a file with a function definition were to be included twice, you'd get an ugly "redefined" error when the function is realistically only in one file.
![Responsive and Infinitely Scalable JS Animations]()
Back in late 2012 it was not easy to find open source projects using requestAnimationFrame()
- this is the hook that allows Javascript code to synchronize with a web browser's native paint loop. Animations using this method can run at 60 fps and deliver fantastic...
![Designing for Simplicity]()
Before we get started, it's worth me spending a brief moment introducing myself to you. My name is Mark (or @integralist if Twitter happens to be your communication tool of choice) and I currently work for BBC News in London England as a principal engineer/tech...
![MooTools ASCII Art]()
I didn't realize that I truly was a nerd until I could admit to myself that ASCII art was better than the pieces Picasso, Monet, or Van Gogh could create. ASCII art is unmatched in its beauty, simplicity, and ... OK, well, I'm being ridiculous; ASCII...
![Scrolling “Agree to Terms” Component with MooTools ScrollSpy]()
Remember the good old days of Windows applications forcing you to scroll down to the bottom of the "terms and conditions" pane, theoretically in an effort ensure that you actually read them? You're saying "No David, don't do it." Too late -- I've done...
It seems a little redundant to check for class existence when you’re trying to create a new class. If the class does exist, then you want yours to be named something else so that it can be used. I would personally want an error in the example above, so I knew to rename the class.
It would make sense to check for the class before instantiating it, but to check for the class before creating it, seems like it could create some confusing situations.
Thanks for this cool idea. Sometime it really becomes hard to follow other developers of the team, so this idea will really help.