Perpetual Promise Generator for AngularJs

getPromiseGenerator.js

(function () {
    'use strict';

    angular
        .module('app')
        .factory('getPromiseGenerator', getPromiseGenerator);

    function getPromiseGenerator($q) {
        var generator = {
            whenPromiseResolves: whenPromiseResolves,
            resolve: resolve
        };

        var deferred = $q.defer();

        return function () {
            return generator;
        };

        function whenPromiseResolves(fn) {
            (function doThisWhenThePromiseResolves() {
                deferred.promise.then(function (resolvedWith) {
                    fn(resolvedWith);
                    deferred = $q.defer();
                    deferred.promise.then(doThisWhenThePromiseResolves);
                });
            })();
        }

        function resolve(resolvedWith) {
            deferred.resolve(resolvedWith);
        }
    }

})();

This is a perpetual promise generator. Every time the promise is resolved a new one is generated. It could be argued that this is taking liberties with the idea of a promise, but if you think of a promise as asynchronous expectation then this generator simply deals with the situation when one expectation always leads to another and in each case we want to run the same code upon resolving.

so in a controller you might have:
var myPromiseGenerator = getPromiseGenerator();
this.whenSomethingInterstingHappens = myPromiseGenerator.whenPromiseResolves;
this.somethingInterestingHappened = myPromiseGenerator.resolve;

then in the link function of a nested directive (where something interesting might happen):
scope.$watch('somethingOfNote',function(value){
parentCtrl.somethingInterestingHappened(value);
});

and in yet another directive (which is interested in interesting things):

parentCtrl.whenSomethingInterstingHappens(updateThisDirectiveBasedOnAnInterthingEventEveryTIme);