Subj : Re: Throwing host exception from host object
To   : netscape.public.mozilla.jseng
From : Brendan Eich <brendan@meer.net>
Date : Wed Mar 17 2004 09:58 am

Igor Bukanov wrote:

> Note also that Rhino supports ECMAScript script extension that can be 
> used to rewrite that as
> 
> try {
>     host.causeExceptions();
> } catch(exception if excetion instanceof MyExceptionType) {
>     // got it
> } catch(exception if excetion instanceof MyExceptionType2) {
>     // got it
> } catch(exception if myExceptionCheck(excetion)) {
>     // got it
> } catch (exception) {
>    // optional catch-all
> }
> 
> Effectively you can use "if arbitrary-boolean-expression" to add a 
> condition-specific handler.

A non-obvious virtue of these guarded catch clauses is that you get an 
automatic rethrow if there is no final unguarded "catch-all" clause.

/be

.