model.js

// The primary function of a **Model** is to manipulate and query data. For example filtering
// an array-type object should happen in a subclass of Model. Another great candidate
// for a **Model** is any object that requires an external resource such as an ajax call.
//
// Basically, any long running or long blocking operation should happen in a model.
//
// **Models** are bindable as well, so you can subscribe to notifications by calling
// `bind` with a callback and an event to subscribe to to recieve events in another object.
//
// **Models** are usually encapsulated in **Views** and rarely, if ever, stand alone. 

propublica.Model = Base.extend({
  // The **init** method copies the passed in attributes to the instance's built in
  // **_attrs** object.
  
  MODEL_CHANGED : "changed",
  
  init : function(attrs){
    this._attrs = this._attrs || {};
    _.extend(this._attrs, attrs);
    this.id = _.uniqueId(this.name || "");
  },
  
  // Access an attribute by key.
  read : function(key){
    return this._attrs[key] || null;
  },
  
  // Set an attribute by key.
  write : function(key, attr){
    var oldAttr = this._attrs[key];
    this._attrs[key] = attr;
    this._onchange(oldAttr);
    return oldAttr;
  },
  
  // delete an attribute by key.
  remove : function(key){
    var oldAttr = this._attrs[key];
    delete this._attrs[key];
    this._onchange(oldAttr);
    return oldAttr;
  },
  
  // The **copy** method returns a copy of the current **Model** with the instance's 
  // attributes filled in.
  copy : function(){
    return new (this.init)(this._attrs);
  },
  
  _onchange : function(oldAttr){
    if(this.MODEL_CHANGED) this.fire(this.MODEL_CHANGED, this.id, oldAttr);
  },
  
  bind : function(e, cb){
    var callbacks = (this._callbacks = this._callbacks || {});
    var list = (callbacks[e] = callbacks[e] || []);
    list.push(cb);
  },
  
  unbind : function(e, cb){
    if(!(this._callbacks && this._callbacks[e])) return;
    var list = this._callbacks[e];
    for(var i = 0; i < list.length; i++){
      if(list[i] === cb) { 
        list.splice(i, 1);
        break;
      }
    }
  },
  
  unbindAll : function(){
    delete this._callbacks();
  },
  
  fire : function(e){
    if(!this._callbacks) return;
    var list = this._callbacks[e];
    if(!list) return;
    for(var i = 0; i < list.length; i++) list[i].apply(this, arguments);
  }
  
});



/// subscribing to events
var T = new propublica.Model();

T.on(T.MODEL_CHANGED, function(){ console.log("event fired"); });