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.
![Welcome to My New Office]()
My first professional web development was at a small print shop where I sat in a windowless cubical all day. I suffered that boxed in environment for almost five years before I was able to find a remote job where I worked from home. The first...
![Introducing MooTools Templated]()
One major problem with creating UI components with the MooTools JavaScript framework is that there isn't a great way of allowing customization of template and ease of node creation. As of today, there are two ways of creating:
new Element Madness
The first way to create UI-driven...
![Form Element AJAX Spinner Attachment Using MooTools]()
Many times you'll see a form dynamically change available values based on the value of a form field. For example, a "State" field will change based on which Country a user selects. What annoys me about these forms is that they'll often do an...
![Styling CSS Print Page Breaks]()
It's important to construct your websites in a fashion that lends well to print. I use a page-break CSS class on my websites to tell the browser to insert a page break at strategic points on the page. During the development of my...
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.