defer = function() {
    var pending = [],
        value, deferred;

    deferred = {

      resolve: function(val) {
        if (pending) {
          var callbacks = pending;
          pending = undefined;
          value = ref(val);

          if (callbacks.length) {
            nextTick(function() {
              var callback;
              for (var i = 0, ii = callbacks.length; i < ii; i++) {
                callback = callbacks[i];
                value.then(callback[0], callback[1]);
              }
            });
          }
        }
      },


      reject: function(reason) {
        deferred.resolve(reject(reason));
      },


      promise: {
        then: function(callback, errback) {
          var result = defer();

          var wrappedCallback = function(value) {
            try {
              result.resolve((callback || defaultCallback)(value));
            } catch(e) {
              exceptionHandler(e);
              result.reject(e);
            }
          };

          var wrappedErrback = function(reason) {
            try {
              result.resolve((errback || defaultErrback)(reason));
            } catch(e) {
              exceptionHandler(e);
              result.reject(e);
            }
          };

          if (pending) {
            pending.push([wrappedCallback, wrappedErrback]);
          } else {
            value.then(wrappedCallback, wrappedErrback);
          }

          return result.promise;
        }
      }
    };

    return deferred;
  }
@ngdoc
@name angular.module.ng.$q#defer
@methodOf angular.module.ng.$q
@description
Creates a `Deferred` object which represents a task which will finish in the future.

@returns {Deferred} Returns a new instance of deferred.