自定义抛出异常

<?php
class myexception extends Exception
{
public function errormessage()
{
$errmessage = "error :".$this->getline()." in ".$this->getfile()."<b> error:".$this->getMessage()
."</b>";
return $errmessage;
}
}
$email="1348405969@qq.com";

try
{
try
{
throw new Exception($email);
}
catch (Exception $e)
{
throw new myexception($email);
}
}
catch(myexception $e)
{
echo $e->errormessage();
}
/* try
{
throw new Exception($email);
}
catch(Exception $e)
{
try
{
throw new myexception($email);
}

catch(myexception $e)
{
echo $e->errormessage();
}
}*/

?>