Can I autoload function files without classes in PHP?

Question

My site is pretty large and I do not use PHP Classes, I do not understand OO good enough yet to re-write my site to use them however I would really like to use the __autoload($class_name) feature that classes use. I rely a lot on functions, I have different function files,
forums.inc.php
blogs.inc.php
user.inc.php
photos.inc.php
general.inc.php

All these files are just functions specific to a certain part of the site, except general.inc.php would have functions that need to be on ever page.

Now is there anyway I could use autoload or make something similar that would load these function files? I once thought about doing it based on the URL, like if the URL had the word forums in it, I would load the forums function file but this would not always work as ever file related to forums does not have the word forum in there URL.

Am I pretty much out of options until I learn to code OO good enough to put all my functions into classes?

//example of the autoload 
function __autoload($class_name){
    include('classes/' . $class_name . '.class.php');
}
$time = new time();
$time->fn1();

Answer 1

I don't think you can, to be honest, not in a straightforward way. In any case, wouldn't it be way nicer to use utility classes? There's nothing to the OOP, look at this:

<?php
    class HTMLUtil {

        public static function filter($str) {...}
        public static function entities($str) {...}
        public static function encode($str) {...}
        ...etc...
    }
?>

Static Helper/Utility classes that group together related functionality are simple to put together, just declare your functions as static:

Declaring class members or methods as static makes them accessible without needing an instantiation of the class.

Now you can use __autoload. You don't have to instantiate those classes to use any of their static functions, and it makes your code more readable (if slightly more verbose). I always find it more satisfying to do something like:

echo HTMLUtil::filter($str);

instead of:

echo filter($str); //scary filter function, where are you from?

If needed, you can also declare a private constructor in your utility classes to prevent them from being instantiated, to emphasize that their 'just a bunch of related functions':

private __construct() {...}

To call a static function from another function within the same class you would do so using the self keyword (which references the same class, and not object or class instance):

public static function foo()
{
    echo self::bar() . '..and some foo';
}