WatchedObject

controllers.application.js

var WatchedObject = Ember.Object.extend({
  "*": null,
  
  setUnknownProperty: function(k,v){
    var self = this;
    self.addObserver(k, function(){
      Ember.run.once(self, 'somethingChanged');
    });
    Ember.defineProperty(this, k, null, v);
    this.notifyPropertyChange(k);
  },
  
  init: function(){
    this._super();
    var self = this;
    Ember.keys(this).forEach(function(key){
      if(Ember.typeOf(self.get(key)) !== 'function'){
        self.addObserver(key, function(){
          Ember.run.once(self, 'somethingChanged');
        });
      }
    }); 
  },
  
  somethingChanged: function() {
    this.notifyPropertyChange('*');
  }
});

var MyTrips = WatchedObject.extend({
  numberOfTrips: (function(){
    return Ember.keys(this).length
  }).property("*")
});

export default Ember.Controller.extend({
  trips: null,
  init: function(){
    this._super();
    this.set('trips', MyTrips.create());
    var i=0;
    var self = this;
    setInterval(function(){
      self.get('trips').set('tripNumber'+i, 'some trip'); 
      i++;
    }, 400);
  }
  
});

templates.application.hbs

{{trips.numberOfTrips}}
<br>
and the 8's trip is: {{trips.tripNumber8}}
<br>
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.10.7",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "1.13.13",
    "ember-data": "2.10.0",
    "ember-template-compiler": "1.13.13",
    "ember-testing": "1.13.13"
  },
  "addons": {}
}