__autoload($class) not working? class not found error

Question

I am following some examples in the PRO PHP AND JQUERY book, but for some reason the examples doesn't work. Even the examples that I downloaded from the books site doesn't work. Not sure whats wrong, because I have done exactly as in the book..

/public/Index.php

include_once '../sys/core/init.inc.php';
$cal = new Calendar($dbo, "2010-01-01 12:00:00"); //ERROR Class 'Calendar' not found

/sys/core/init.inc.php

    function __autoload($class)
    {
        $filename = "../sys/class/class." . $class . ".inc.php";
        if ( file_exists($filename) )
        {
            include_once $filename;
        }
    }

/sys/class/class.calendar.inc.php

class Calendar extends DB_Connect
{
    private $_useDate;
    private $_m;
    private $_y;
    private $_daysInMonth;
    private $_startDay;

    /**
     * Create a database containg relevant info
     *
     * @param object $dbo a database object
     * @param string $useDate the date to build calender
     */

    public function __construct($dbo=NULL, $useDate=NULL)
    {
        /*
         * Call the parent constructor to check db object 
         */
        parent::__construct($dbo); 
    }


}

This is very annoying since every chapter in the books builds on this simple foundation. My guess is that __autoload() is the problem, but I have no idea..

Answer 1

The filepaths do not point to the right spots.

A better idea would be something like this in Index.php...

define('DOCROOT', dirname(__FILE__));

...and then modify your __autoload() like so...

function __autoload($class)
{
    $filename = DOCROOT . "/sys/class/class." . strtolower($class) . ".inc.php";
    if ( file_exists($filename) )
    {
        include_once $filename;
    }
}

You should strotlower() the filename before including it, as your class is Calendar but your filename has calendar.

Answer 2

First of all, you are discouraged from using __autoload() in new code as it MAY BE DEPRECATED OR REMOVED IN THE FUTURE, according to official doc; instead, use spl_autoload_register() like so:

//first define a custom function
function myAutoLoader( $className ){

    $path = strtolower( path/to/your/class/ . $className . '.php' );

    include_once( $path );

}

Notice how we strtolower() the $className. This to make sure that the class name ( usually starts with upper case ) tallies with the filename ( usually all in lower case ). In some environment ( especially Windows ), this may not be necessary, but just to be on a safer side. For example, I do not have to in my development environment which is Windows but my production environment( debian ) will not take it.

Then pass that function name as argument into spl_autoload_regsiter. Note that the function name is string

 //Now use spl_autoload_register()
spl_autoload_register( 'myAutoLoader' );

If you wish to catch exception, you may do something like this in your custom function like so:

//first define a custom function with exception handling
function myAutoLoader( $className ){

    $path = strtolower( path/to/your/class/ . $className . '.php' );

    include_once( $path );

    if( !class_exists( $className, false ) ){
       throw new RuntimeException( 'Class '. $className . ' has not been         
       loaded yet' ); 
    }
}

//then the spl_autoload_register(), just like before
spl_autoload_register( 'myAutoLoader' );

You will then have to catch the thrown exception when declaring your class.