Subj : Re: Throwing host exception from host object
To   : Larry Blanchette <LBlanchette@Grandcentral.com>
From : Igor Bukanov <igor@fastmail.fm>
Date : Wed Mar 17 2004 11:47 am

Larry Blanchette wrote:
> In rhino, I would like throw from a host object my own scriptable types as
> catchable exceptions of "my type" in javascript.  I seems that 
> 
> extending EvaluatorException 
> 
> and using
> 
> Context.throwAsScriptRuntimeEx(ex);
> 
> is the path to follow but it does not allow me to propagate my type.  The
> exception is caught as either "internalError" in the case of an evaluator
> exception and "JavaException" otherwise. Do I need to extend ScriptRuntime
> and override getCatchObject(Context cx, Scriptable scope, Throwable t) to
> handle and convert my exceptions (didn't want to go there)?
> 
> So if have 
> 
> class MyExceptionType extends ScriptableObject
> 
> and in host object I throw
> 
> Context.throwAsScriptRuntimeEx(myScriptable);  // illegal
> 
> 
> then i would
> 
> try {
> 	host.causeExceptions();
> } catch(exception) {
> 	if(excetion instanceof MyExceptionType) {
> 		// got it
> 	}
> }

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.

Regards, Igor

.