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13 years ago
I'm running PHP 5.3.4 on Windows 7 and had some difficulty autoloading classes using class_exists(). In my case, when I checked for the class and it didn't exist, class_exists automatically threw a system Exception. I was also throwing my own exception resulting in an uncaught exception.

<?php
/**
 * Set my include path here
 */
$include_path = array( '/include/this/dir', '/include/this/one/too' );
set_include_path( $include_path );
spl_autoload_register();
/**
 * Assuming I have my own custom exception handler (MyException) let's
 * try to see if a file exists.
 */
try {
    if( ! file_exists( 'myfile.php' ) ) {
        throw new MyException('Doh!');
    }
    include( 'myfile.php' );
}
catch( MyException $e ) {
    echo $e->getMessage();
}
/**
 * The above code either includes myfile.php or throws the new MyException
 * as expected. No problem right? The same should be true of class_exists(), 
 * right? So then...
 */
$classname = 'NonExistentClass';
try {
    if( ! class_exists( $classname ) ) {
        throw new MyException('Double Doh!');
    }
    $var = new $classname();
}
catch( MyException $e ) {
    echo $e->getMessage();
}
/**
* Should throw a new instance of MyException. But instead I get an
* uncaught LogicException blah blah blah for the default Exception
* class AND MyException. I only catch MyException so we've got on
* uncaught resulting in the dreaded LogicException error.
*/
?>

By registering an additional autoload handler function that did nothing, I was able to stop throwing the extra Exception and only throw my own.

<?php
/**
 * Set my include path here
 */
$include_path = array( '/include/this/dir', '/include/this/one/too' );
set_include_path( $include_path );
spl_autoload_register();
spl_autoload_register( 'myAutoLoad' ); // Add these two and no worries...
function myAutoLoad() {}
/**
 * By registering the additional custom autoload function that does nothing
 * class_exists() returns only boolean and does NOT throw an uncaught Exception
 */
?>

Found this buried in some search results. I don't remember the page URL but if it would have been here it might have saved me some time!
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