any idea why?

But I encountered a bug:

The preg_match_all statement did not work in my PHP 5.1.2 distribution. The result array was empty. So I had to change it to the following:

if($buf = fread($php_file, filesize($file_path))) { $result = array();
if(preg_match_all(”%(interface|class)\s+(\w+)\s+(extends\s+(\w+)\s+)?(implements\s+\w+\s*(,\s*\w+\s*)*)?{%”, $buf, $result)) {
foreach($result[2] as $class_name)
…

SmartLoader fails with an error if the class was not found. However, it may have been called through class_exists(), in which case a non-existent class name is perfectly OK as an argument.

IMHO the trigger_error is not necessary, so I just stripped it, replacing
if(!$ldr->loadClass($class_name)) { trigger_error("SmartLoader: Cannot load class '".$class_name."'", E_USER_ERROR); }

by

Harry had stated toward the beginning of this thread that

…calls to require_once, even when a file has been included, can get expensive and it looks like this approach would really help reduce that.

But how much cheaper is a call to __autoload() that searches the directory structures in the include path for some generic file name? Aren’t you essentially mimicking the functionality that require, require_once, include and include_once already provide (that is, searching the include path for the desired file)? It would be interesting to test and compare these two methods.

I worry that many programmers are going to use __autoload() as a wrapper to require_once() and add accomplish nothing but add complexity to their applications. The only time I can see a benefit to using __autoload() is in the event that an object must be instantiated whose class isn’t known until runtime. And even then you’d need to be extremely careful for the security reasons mentioned above.

</devils_advocate>

I usually tweak autoload just slightly to do the following:

GLOBAL_LIB_DIR.'Classes/Class1.php',
'Class2'=>GLOBAL_LIB_DIR.'Classes/Class2.php',
'Interface1'=>GLOBAL_LIB_DIR.'Interfaces/Interface1.php',
);

and so on and so forth.

This allows me to easily define where any given class / set of classes will reside. I generally try to keep everything in a common lib folder, but within that you’ll still want to break down into subfolders for different “packages”.

But you don’t need the require statements if you use this method. A useful thing when you have a large app/site with loads of classes.