Here be dragons and black magic!

Dirty Casting

<?php
class Caster
{
    /**
     * Casts an Array to an instance of a class
     *
     * This method will return an instance of the given $className with all
     * elements in the array being public members of the instance. The method
     * uses serialization to work, so no constructor will be called to get the
     * instance of $className. The returned instance may behave unexpectedly
     * when the array contains values that are non-public members in the class.
     *
     * @param  array	$array
     * @param	string	$className
     * @return	Mixed	an instance of $className
     */
    public static function arrayToObject(array $array, $className)
    {
        if (!is_string($className)) {
            throw new \InvalidArgumentException('Argument 2 must be a String');
        }
        return unserialize(
            sprintf(
                'O:%d:"%s"%s',
                strlen($className),
                $className,
                strstr(serialize($array), ':')
            )
        );
    }
    /**
     * Casts any object instance to a different class
     *
     * This method will cast the object instance passed to it an instance of
     * the class given as the second argument. If any of the arguments is not
     * of the expected type, the method will throw an InvalidArgument Exception.
     * The method uses serialization to work, so no constructor will be called
     * to cast the instance of $className. This might put the new instance into
     * an invalid state.
     *
     * @throws	\InvalidArgumentException
     * @param	Object	$instance
     * @param	String	$className
     * @return	Mixed	an instance of $className
     */
    public static function castToObject($instance, $className)
    {
        if (!is_object($instance)) {
            throw new \InvalidArgumentException(
            	'Argument 1 must be an Object'
            );
        }
        if (!class_exists($className)) {
            throw new \InvalidArgumentException(
            	'Argument 2 must be an existing Class'
            );
        }
        return unserialize(
            sprintf(
                'O:%d:"%s"%s',
                strlen($className),
                $className,
                strstr(strstr(serialize($instance), '"'), ':')
            )
        );
    }
}