Service for sharing state across controllers. Supports a notion of baseline states that can be rolled back to. You can also set (and sync to) new baselines.

gistfile1.js

angular.module('myModule').factory('SharedMetaData', function(SharedState) {
  return SharedState.init({
    what: 'Array Stuffs',
    arr: [1,2,3,4]
  });
});

gistfile2.js

angular.module('myModule').controller('SomeCtrl', function($scope, $q, SharedMetaData) {
  $q.when(SharedMetaData()).then(function(smd) {
    $scope.smd = smd;
  });
});

gistfile3.js

angular.module('myModule').controller('SomeCtrl', function($scope, $q, SharedMetaData) {

  var deferred = $q.defer();
  
  deferred.promise.then(SharedMetaData.set);

  $timeout(function() {
    deferred.resolve({
      what: 'new array stuffs',
      arr: ['a', 'b', 'd']
    })
  }, 5000);
});

SharedState.js

angular.module('myModule').factory('SharedState', function($q, $timeout) {
  return {    
    init: function(defaults) {
      var payload = {}
        , deferred
        , self = this;
      
      defaults = defaults || {}; // You can set initial defaults here
      
      var SharedState = function(init_args) {
        if(deferred) { return deferred.promise; }
        
        deferred = $q.defer();
          
        $q.when(defaults).then(function() { // Might only be promised defaults.
          
          // Set defaults if any init_args - makes sure the next time we reload
          // we do so with the new set of defaults;
          if(init_args) {
            angular.forEach(init_args, function(val, key) {
              defaults[key] = val;
            });
          }
          
          // Do something with init_args?
          angular.forEach(defaults, function(val, key) {
            payload[key] = angular.copy(val);
          });
          
          // Make good on our promises
          deferred.resolve(payload);
        });
        
        return deferred.promise;
      };
      
      SharedState.reload = function() {
        deferred = null;
        return SharedState.apply(self, arguments);
      };
      
      return SharedState;
    }
  };
});