[squeak-dev] Re: Algernon modification to register as an eventListener into HandMorph

Andreas Raab andreas.raab at gmx.de
Sat May 17 22:50:59 UTC 2008


Igor Stasenko wrote:
> Well, i think its more logical to do copy of events in
> EventRecorderMorph  and RemoteHandMorph
> instead of HandMorph class. Really why such special event handlers
> like above, which collecting events, should rely on different class to
> receive a copy of events, instead of making copy themselves?

Robustness. I didn't even know that EventRecorderMorph and 
RemoteHandMorph kept the last events and I have no idea whether that can 
cause problems or not. Creating copies for the listeners (which are 
different from filters btw; listeners are assumed to be passive and 
consequently copying the event only serves the purpose to decouple the 
listener processing from the internal processing later) makes the whole 
mechanism more robust at very little cost. New clients simply cannot 
break later processing by accidentally modifying the event. You have to 
understand that this is a *very* low-level hook into the system - making 
an error in your code *will* completely screw the environment so a 
little caution is in order I think.

Cheers,
   - Andreas



More information about the Squeak-dev mailing list