Key Value Observation (ala Cocoa) in GWT ?

Question

Hi all,

There are these 2 frameworks out there in the same "cloud application" space as GWT: Sproutcore and Cappuccino.

Cappuccino is Cocoa for the web, Sproutcore is Cocoa-like and one very central idea in both is Key Value Observation where the framework itself provides the glue to change all dependencies of an object when it changes, and you only have to declare those dependencies.

If that was too poorly expressed please see this presentation: http://www.infoq.com/presentations/subelsky-sproutcore-intro

Since the pattern reduces the amount of code you type it reduces the number of bugs. Maybe it's too much to ask but I would like to have that and all the benefits of Eclipse/compiler that come with GWT.

Is there support for this in GWT, or a library already developed? Or maybe there is support in some of the component libraries for GWT out there?

Thanks

Answer 1

Data bindings is a feature a lot of people want to add to core GWT. It was one of the things on top of the list when the GWT developers asked what people wanted post 2.0.

I only know of one generic data binding library for GWT;

http://code.google.com/p/gwt-beans-binding/

It allows you to create generic bindings as long as your beans implement a special property observation interface.

The main two problems with implementing data bindings in GWT is;

• Java is a not a dynamic typed language like Objective-C, and
• GWT does not support reflection

My guess is that GWT core developers will come up with something that uses deferred binding to generate the bindings at compile time. Which will also give us type-checking on the bindings which is nice.