Question

I’m developing a library for guitar chords. In some files on the library I have something like this:

require_once "lib/GuitarChord.php";
require_once "lib/Chord.php";
require_once "lib/Key.php";
require_once "lib/Tuning.php";

How can I make this library so it doesn’t need to know where the other library files are?

This way a person could have the library files in any directory?

Answer 1

Create autoloaders for all locations where these classes might be.

For Example:

//AUTOLOADER
function class_autoloader($class) {

   // presumes classes are in './classes'
   $folders = array(
     './', './../', './../../'  
   );
   $directories = array(
     'classes','lib',  ''
   );
   $dir = dirname(__FILE__);
   $theClass = '/' . $folderedClass . '.php';


   foreach($folders as $folder){
       foreach($directories as $directory){
           $theInclude = $dir.$folder.$directory.$theClass;

           if (file_exists($theInclude) && include_once($theInclude)) {
              return TRUE;
           } 
       }
   }

  trigger_error("The class '$class' or the file '$theClass' failed to spl_autoload ", E_USER_WARNING);

  return FALSE;
}

spl_autoload_register('class_autoloader');

Then if you want to load the Chord Class and you know it is in your lib folder, the autoloader will do the work for you when you do:

new Chord();

You can attach many different autoloader callbacks with spl_autoload_register