Description:
------------
The fundamental behavior of "__toString() must not throw an exception" needs to be changed.  This problem is completely antithetical to object oriented design, and just doesn't even make sense.

class Template{
function __construct($path){
$this->path = $path;
}

function __toString(){
if(!file_exists($this->path)){
throw new Exception('Path does not exist');
}else{
//process template
}
}

$Template = new Template('/path/does/not/exist.php');
echo (string)$Template;

There is absolutely no sane reason that this should be a fatal php error.

Test script:
---------------
class Template{
function __construct($path){
$this->path = $path;
}

function __toString(){
if(!file_exists($this->path)){
throw new Exception('Path does not exist');
}else{
//process template
}
}

$Template = new Template('/path/does/not/exist.php');
echo (string)$Template;


Expected result:
----------------
Raise a regular exception.  Why would raising an exception ever be not allowed?  What is the point?

Actual result:
--------------
__toString() must not throw an exception

Pretty much the worst result possible.  Unrecoverable fatal error.  Why?  What is the point?