Morphs and Data Question

Hi Eric,

for general "reacting to changes", you could an observer pattern. I think this answer from StackOverflow explains it quite well: https://stackoverflow.com/a/17083241/13994294 For example in Squeak, you could take a look at the Pluggable morph implementations in the system categories Morphic-Pluggable Widgets as well as ToolBuilder-Morphic. For instance, in PluggableButtonMorph, you can see that the communication between morph and model is realized by defining selectors on the morph that will be performed to get necessary data and that can be signaled using the observer pattern to update the visual representation. See PluggableButtonMorph >> #update:.

Apart from that, you could also take a look at the "Object Events" pattern in Squeak, see Object >> #when:send:to: + overloads and senders. Personally, I prefer the "normal" observer pattern the most time because it feels less like coupling the morph and the model too strong to each other, and it gives you greater flexibility without necessarily defining one selector per event type on the morph class.

(Last but not least, it would be a possibility to store closures that were generated by the morph in the model and to evaluate them on every change. However, this is usually an anti-pattern because it creates a very strong coupling between the morph and the model, so I would not really recommend using this approach ...)

To learn more about the underlying design patterns, you could look up in the encyclopedia of your choice the terms "Observer pattern", "MVC", and "MVVM". I hope that helps, and if you have further questions, please don't hesitate to ask them. :-)

Best,

Christoph