trapped

What is trapped?

Trapped is a library for Amber that aims to create bidirectional data-binding UI for Amber. When it is for Amber, how else should it be called than "trapped"?

It is inspired by AngularJS. But it does not aim to be hard port of AngularJS into Amber, it just tries to bring some of the good things, but stay true to Amber/Smalltalk way of doing web UI.

What stage it is in?

Very early. Nevertheless, very basic things are already working. You can try it, though it still misses a lot.

What is working:

• viewmodel -> view update propagation
• showing simple data in view.

What is missing:

• optimizations ;-)
• iterations in view
• view -> viewmodel change propagation

How can I try it?

Clone this repo, with submodules as well (amber is bundled as submodule). Then start the server: node vendor/amber/server/server.js. It start on port 4000. Visit http://localhost:4000/demo.html in your browser. Amber IDE opens.

Trapped itself is in Trapped-Frontend and Trapped-Backend packages. The demo page itself is in demo.html and its code is in Trapped-Demo package, in classes App and AppView. Other classes in Trapped-Demo are just prototype implemenations of Trapped building blocks. They may be deleted in the future or move to frontend/backend packages when they mature. Anyway, the code of the page is in App (the view model) and AppView (the view). The App instance is put into global AppVM variable in demo.html initialization.

Trapped is pretty light: the view model wraps any object (via payload:, as seen in App >> initialize). The view is subclass of plain Widget, but inside it, uses of trapShow: (which itself uses trap:read:) and trapDescend: allows you to bind data from view model.

To see viewmodel->view update working, try

AppVM modify: #('items') do: [ :old | old, { '!' } ]

The number and list of items should update. If you do

AppVM modify: #('title') do: [ :old | 'My title' ]

The title of the page as well as header should be updated.

The modify:do: should be used for update since it changes as well as signals the change. It is planned that read:do: and modify:do: will guard the data by doing deep copies behind the scene against remembering and modifying out of sync. If you wish to, you can change the raw data you put into payload: by hand, but then be sure to call AppVM changed: #('title') or similar (you can do AppVM changed: #() to signal everything in AppVM has changed, but then everything depending upon it will redraw).