Creates a computed property that persists into local storage, all instances share the same value for the same property, intended to be used for controllers.

ember.computed.stored.js

/*
  Creates a computed property that persists into local storage, all
  instances share the same value for the same property.
 
  App.AuthController = Ember.Controller.extend({
    token: Em.computed.stored()
  });
  
  controller = App.__container__.lookup('controller:auth')
  contorller.set('token', 'abc123foo456bar')
  
  **Page is reloaded**
  
  controller.get('token')
  -> 'abc123foo456bar'
*/
void function() {

function keyFor(obj, property) {
  var ns = obj.constructor.toString();
  return ns + '.' + Em.String.underscore(property);
}

function getItem(obj, property) {
  var key  = keyFor(obj, property),
      data = localStorage.getItem(key);
  if (data) {
    return JSON.parse(data).data;
  } else {
    return null;
  }
},

function setItem(obj, property, value) {
  var key = keyFor(obj, property);
  if (value === null) {
    localStorage.removeItem(key);
  } else {
    localStorage.setItem(key, JSON.stringify({ data: value }));
  }
  return value;
}

Em.computed.stored = function() {
  return Em.computed(function(key, value) {
    if (arguments.length === 1) {
      return getItem(this, key);
    } else {
      setItem(this, key, value);
      return value;
    }
  });
};

}.call(this)