Last week I learned that classes can be included in your project by writing an __autoload() function. Then I learned that using an autoloader isn't only a technique but also a pattern.
Now I'm using the autoloader in my project and I've found it very very useful. I was wondering if it could be possible to do the same thing with functions. It could be very useful to forget about including the right PHP file with functions inside it.
So, is it possible to create a function autoloader?
There is no function auto-loader for functions. You have four realistic solutions:
Wrap all functions into namespacing classes (context appropriate). So let's say you have a function called string_get_letters. You could add that to a class called StringFunctions as a static function. So instead of calling string_get_letters(), you'd call StringFunctions::get_letters(). You would then __autoload those namespaced classes.
Pre-load all functions. Since you're using classes, you shouldn't have that many functions, so just pre-load them.
Load functions prior to using them. In each file, require_once the function files that are going to be used in that file.
Don't use functions in the first place. If you are developing OOP code (which it seems like you are anyway), there should be little to no need for functions at all. Everything you would need a function (or multiple) for, you could build in a OO manner and avoid the need for functions.
Personally, I'd suggest either 1, 2 or 4 depending on your exact need and the quality and size of your codebase...