Re: Exceptions and Objects

On Mon, Aug 14, 2000 at 10:56:36AM -0500, Jonathan Scott Duff wrote:
> On Mon, Aug 14, 2000 at 04:09:41AM -0600, Tony Olekshy wrote:
> > $@->CanFoo is an example of semantics that determines whether or
> > not the exception is caught; stringification may be an example
> > of semantics that comes into play when an exception is caught.
> 
> Ah, this is why I started asking I guess.  Some people were proposing
> a try/catch like the following:
> 
> 	try { } 
> 	catch SomeException { }
> 	catch SomeOtherException { }
> 	finally { }
> 
> which seems to only catch exceptions based on name.

Yes, but an exception has multiple names as it is a class name
and you perform ->isa(name)

>  Which implies to
> me that, for exceptions to have useful semantics, they'd have to be
> rethrown after they're caught.  I like the following, but it would
> also seem that exceptions that aren't handled here would have to be
> rethrown so that an upstream catch could handle them.
> 
> 	try { } 
> 	catch {				# ALL exceptions
> 	    switch ($@) { 
> 		case ^_->name eq 'IO'	{ ... }
> 		case ^_->canFoo 	{ ... }
>                 throw $@;		# No cases matched, rethrow
> 	    }
> 	}
> 	finally { }

This is always an option for the programmer.

Graham.