[Cuis-dev] Rerendering when touched: Experiments in simplifying UI development in Cuis inspired by Mithril.js

[Hilaire Fernandes]

Hi Paul,

Coincidentally, a few weeks ago, I was reading about model-less GUI, not 
any particular implementation like the ones you referred in your email, 
but about the general idea to re-construct the whole or part of the GUI 
when an event occurs.

It is true that it is not obvious to track the source of events with the 
observer pattern: triggered in one place, hooked in another ones. The 
tools to help the developer comprehension of events is not really there. 
The fact that it is based on symbol and not object does not help. I 
guess that what we all do is to search for symbol in the source code, 
i.e. #selected.

Regarding the model, Morph itself is very neutral regarding the 
necessity to have one. Pluggable morph requires one but many others 
embed it (TextParagraphMorph, TextEnty Morph). And when required, there 
are generic models (ValueHolder, ListModel, ...).

*A few points of thinking.*

It is possible to hook programmatically mouse/keyboard events to a 
Morph. In your example the handlesMouseDown: and mouseButtons1xxx can be 
set programmatically, so it avoid subclassing. It may help to compose 
the GUI with sub morphs, using sub morphs improves the efficiency. In 
your example the whole rectangle  of the GUI is rebuild even if only a 
small part needs to be updates.

I am wondering if the simplicity you get from just rebuilding GUI comes 
with a hidden cost.

Concerning model, don't you need one at some point to represent the 
state of your application ? So most the time the model is not a bargain 
as it already exists. Ok may be not for your converter example.

In the Cuis-Smalltalk-UI, there is a UI-Mold package to describe field 
input form, with data validation. It should be possible to add a kind of 
computed ouput object.

Hilaire

-- 
GNU Dr. Geo
http://drgeo.eu
http://blog.drgeo.eu
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