Separate Attributes Mixin (#2526)

[matthewwithanm]

As suggested by @tgriesser, I've implemented the feature I suggested in #2526 (a mixin for adding observable attributes to arbitrary objects). It works just like Backbone.Events, in that it's used with _.extend. There's not much new here; just making the related methods usable on non-Models.

var object = {};
_.extend(object, Backbone.Attributes);
object.on('change', function(){ alert('changed'); });
object.set('someAttribute', 'value');

Or on a view:

class TinyWidget extends Backbone.View
    _.extend @prototype, Backbone.Attributes

widget = new TinyWidget
widget.on 'change:color', -> alert 'color changed!'
widget.set color: '#0000FF'

[jashkenas]

Very cool refactor -- but I think it's a bit too granular and slice-and-dicey for us. 95% of Backbone users probably won't encounter a need for this mixin where simply using a model wouldn't be easier. Makes for a nice extraction or plugin, though.

[matthewwithanm]

I understand. Thanks for taking a look!

[mateusmaso]

@matthewwithanm I really liked the idea and it would fit very nicely for people who wants the same behavior of attributes for Collections (meta) and Views (options).. I don't think that everything must be a model to hold attributes (models have much more meaning), but making it granular only brings reusability to not reinvent the wheel for get, set and change events..

@jashkenas In general, Backbone should care more about separating concerns into modules instead of guessing how many users would use it.. I like the simplicity of this lib, but it should be also simple to extend and reuse functionalities for framework purposes.

[akre54]

Here's a simple script that pulls out @matthewwithanm's changes into a standalone plugin if you so choose:

Backbone.Attributes = _.extend({}, Backbone.Events);
var modelMethods = ['get', 'set', 'unset', 'clear', 'has', 'changed', 'hasChanged', 'changedAttributes', 'previous', 'previousAttributes'];
var wrappedMethods = ['get', 'set', 'clear', 'changedAttributes'];

_.each(modelMethods, function(method) {
  var fn = Backbone.Model.prototype[method];
  Backbone.Attributes[method] = _.contains(wrappedMethods, method) ?
     function() { this.attributes || (this.attributes = {}); return fn.apply(this, arguments) } : fn;
});

Backbone.Attributes._validate = function() { return true; }; // hacky, but works


// Later
var view = new Backbone.View;
_.extend(view, Backbone.Attributes);
view.set(...);

EDIT: Now available as a full-blown plugin: https://github.com/akre54/backbone.attributes