$a = new Exception("foo");
try {
    throw $a; //Line 1
} catch (Exception $e) {
    throw $a; //Line 10;
}

<?php
class DumbException extends Exception {
    /**
     * Cleanup anything we need before serialisation
     *
     * @return  string[]    An array of member varible names to serialize
     * @see     http://php.planetmirror.com/manual/en/language.oop5.magic.php
     */
    public function __sleep() {
        return array('string','code');
    }

    /**
     * Compare against another DumbException for equality.
     *
     * Since two exceptions can be !== because the trace / line / file
     * information is different, we need to do this.
     */
    public function cmp(DumbException $e) {
        return (serialize($e) == serialize($this));
    }
}

print '<pre>';
$a = new DumbException();
$b = new DumbException();


try {
    try {
        throw $b;
    } catch (Exception $e) {
        throw $a;
    }
} catch (Exception $e) {

    var_dump($a === $b);
    var_dump($a == $b);
    var_dump($b === $e);
    var_dump($b == $e);
    var_dump($a === $e);
    var_dump($a == $e);

    var_dump($b->cmp($e));
    var_dump($a->cmp($e));
}
print '</pre>';
?>