Re: Exception and selector performing

[Richard Frith-Macdonald]

On 8 Aug 2004, at 20:18, Stefan Urbanek wrote:

> Additional information ...
>
> On 2004-08-08 21:13:41 +0200 Stefan Urbanek <stefan@agentfarms.net> 
> wrote:
>
> > Hi,
> > Here is the situation: I have DO connection: [Observer] <-----> 
> > [Server]. I do:
> > 1. send oneway message from Observer to Server
> > 2. server does something and uses
> >     performSelectorOnMainThread:@(notyfyObserver)
> >     withObject:self
> >     waitUntilDone:NO'
> > 3. 'notifyObserver' is run in server and it sends a message to 
> > Observer
> > 4. when there is an exception in an observer method it is swallowed
> > And (4.) is the problem, as it is really dificult to debug any 
> > application if there is an exception. How do I know that there was an 
> > exception?
>
> All used observer methods are oneway, what explains why the exception 
> is ignored. However, there is no feedback at all. At least some 
> message shold be printed or something.

As the method is oneway, there is no way that exceptions can be 
propagated back to the  process which sent the message.
Perhaps we can/should change GNUstep to log these exceptions ... but 
I'm not sure it's really worthwhile.  If MacOS-X does this, I'd change 
the current behavior to improve compatibility, but otherwise I don't 
think it should be changed.

For the purposes of debugging softwaqre you are working on the solution 
is trivial ... just use an exception handler in the observer method to 
trap any exceptions and print an error message.