> 1. Why is it completely unnecessary to use underscore?
I don’t see the need for using it - I’m no expert on underscore but looking
through the API again there’s nothing in there that I miss. If you want to
load another library that’s up to you.
> 2. Why is it not good to enable loose coupling using the message system
> instead of manually attaching event handlers?
You’re using a long winded way of achieving something simple that is already
done by the framework; this code:
item.addListener('focusout', () => {
console.log('change', item);
var msg = new qx.event.message.Message();
msg.setName('formItemChange');
msg.setSender(item);
qx.event.message.Bus.dispatch(msg);
});
});
fires a change event every time the user leaves the field regardless of whether
it has changed or not (so I’d suggest that’s a bug), and implies that a global
message type of “formItemChange” is enough to be unique within the application
for all subscribers to listen to. I would have thought that if you have more
than just a few fields in your application this could become difficult to
manage.
Anyway, the message you are passing refers to the UI widget and not the model
object which means that your event handler is pretty close coupled to the exact
UI implementation - you can’t change the widgets without impacting your event
handler logic, and you can’t have multiple UIs refer to the same model object
(e.g. a wizard or detail view as well as a summary view).
IMHO it is generally more useful to have events on a particular model object
(ie not a global broadcast), in which case this code is more useful:
formModel.addListener(“changeText”, function(evt) {
console.log(“formModel.text changed to “ + evt.getData());
});
You’re right that if you need to broadcast a global change where the
subscription is not to any specific object then using qx.event.message.Bus is a
valid pattern, although that didn’t appear to be what you were trying to
achieve.
> /Two things that might help in the future are to provide examples in the
> playground (see the above link) and to write in Javascript, not
> typescript/coffeescript/etc - it’s much easier to understand and help
> feedback examples if it can just be copy & pasted into the playground as a
> working example/
>
> I think coffeescript is more readable, but that of course is quite personal.
> I will (and have) use the javascript versions in the future.
The playground does not support coffeescript, and while people on the list use
coffeescript/typescript (and presumably others) the main language is native
javascript and you’re more likely to get help on specific examples if you stick
to it because the playground makes it much easier to exchange ideas.
Personally I find it off putting because it’s an unfamiliar syntax but that
doesn’t mean you shouldn’t use it.
John
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