Re: Ada-Oriented GUI

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 18/03/2018 14:33, Jeffrey R. Carter wrote:
> I've written on here before that I think the traditional 
> register-callbacks-and-call-a-procedure GUI interface is a hack only 
> suitable for sequential languages, and attempted to describe my idea of 
> how a GUI for a concurrent language like Ada should work. Some have 
> expressed the opinion that such an interface is not possible.

Why do you believe that event-loop architecture is better than callback 
one? In the latter there at least no need to have an explicit loop and 
more importantly it can be made type safe if callback are primitive 
operations of interfaces.

As Randy already mentioned, your design is quite close to Windows GDK, 
but very different from other architectures.

In any case I do not see how this responds to major challenges of GUI 
design, e.g. structured filtering of events (widgets swallow events and 
re-emit higher-level ones) or inversion when a button emits events, but 
it is the handler that must process them, so the case-statement or 
dispatching choice constrained by button interface must be in the 
handler code, not in the button or its descendant.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de