[Dev] Problem with collection notifications

[John Anderson]

Ted Leung wrote:

>
> On Sep 24, 2005, at 3:07 PM, John Anderson wrote:
>
>> Yes in some cases we don't want any notifications. Consider this case:
>> wxWidgets handles the click, updates the selection on the screen and
>> tells us about the change. As a result we store the change in the
>> selection. The selection is a change to data that causes a  
>> notification,
>> which causes a new unnecessary update to the screen. So typically when
>> the system updates the screen we only need to save the change. When  the
>> data changes as a result of something the system can't handle we want
>> notifications so we can update the screen. There are many other  similar
>> examples like this that crop up in practice.
>
>
> It sounds like things like the selection should not be subscribing to  
> notifications.
> In general, I don't see a way to solve this problem without building  
> UI knowledge
> into the notification mechanism.

An alternative to building UI knowledge into the notification mechanism 
is to use synchronous notifications and let the guy you notify decide 
when to ignore notificaitons.

>
> Ted