Added asynchronous module initializers. #792

andru · 2013-11-23T10:44:26Z

This pull request adds asynchronous module initializers using jQuery Deferred objects.

It adds three new properties to Marionette.Module:

`_deferReady`

This is a jQuery Deferred object intended for internal use by Marionette.Module.

`ready`

This is a jQuery Promise object which will be resolved or rejected based on the result of any defined asynchronous initializers. It is intended for use as a "public" property.

`_initializerPromises`

This is a Marionette.Promises instance (see below)

It adds one event and corresponding triggerMethod:

ready

The ready event will be triggered when the ready promise has been resolved.

It adds one new method:

addAsyncInitializer

This adds an asynchronous initializer. The callback function should return a promise which will be resolved or rejected when complete. If it returns any other value it will be marked as resolved, but in that case a standard initializer should be used anyway.

It adds one new Marionette object

Marionette.Promises

This is modelled very closely on Marionette.Callbacks, and indeed there may be some way to combine their functionality, but I didn't want to mess with such a core dependency. Essentially it's the same, but the run method adds the return value of the callback to an array, and returns a new promise. When all items in the array are resolved, the promise will be marked as resolved.

This pull request allows application code (other modules, routers, etc) to wait until all asynchronous module dependencies have resolved before continuing. Eg.
MyModule.ready.done(function(){ /*do something*/ });
or
MyModule.on('ready', fn)
The downside to the event-based approach is that only handlers bound before the event will be notified. By using the ready promise object one can use MyModule.ready.done(fn) without caring whether the module has just started, or was started and resolved long ago.

Additionally, using the promise objects with jQuery.when can define multiple module dependencies
Eg.
$.when(FirstModule.ready, SecondModule.ready).done(function(){ /* do something */ });

andru · 2013-11-23T10:48:03Z

src/marionette.promises.js

+        //call the callback and add it's return value (should be a promise)
+        //to the promises stack
+        //for convenience, the callback is provided with a deferred object
+        //it can use to resolve/reject a non-promise asychronous dependency


Note that for convenience callbacks are provided with a jQuery deferred object as their second argument. I'm not sure if this is necessary or just overhead...

eethann · 2013-12-08T16:39:07Z

Quick note from a user: we are invoking browser browser geolocation in a marionette app and would find this very helpful.

jasonLaster · 2013-12-29T23:50:35Z

src/marionette.module.js

@@ -27,6 +45,12 @@ _.extend(Marionette.Module.prototype, Backbone.Events, {
  addInitializer: function(callback){
    this._initializerCallbacks.add(callback);
  },
+  // Asynchronous initializers nitializers are run when the module 


Small typo -
+ // Asynchronous initializers are run when the module

samccone · 2014-01-15T23:12:16Z

this concept is resolved in #845

andru · 2014-01-16T08:52:04Z

@samcone - #845 does not introduce asynchronous initializers. It introduces an initialize function which is called as a constructor much like in views, models etc: useful but completely distinct functionality, and doesn't introduce any asynchronous behaviour.

This pull request allows the definition of asynchronous resources which must be loaded at module start, via initialize functions. These return a promise to the module which they will resolve when they are ready. After all these initializers have resolved their promises, the module then fires a 'done' event, allowing observers both inside and outside of the module to know that it is ready.

samccone · 2014-01-16T14:05:08Z

k @andru going to keep open, for more discussion. This is kinda @cobbweb's baby so I will let him take it from here.

Thanks for the work so far!

andru · 2014-01-16T14:08:43Z

thanks @samccone. @cobbweb if you need a use case or any further rationale for this just give me a shout.

ccamarat · 2014-01-17T04:29:02Z

I think this is great. jQuery's Promise library supports both async and synch handlers. If you $.when($.noop).then(doSomething);, doSomething will execute immediately. I'd prefer to see addInitializer retrofitted the same way instead of having to call a new addAsyncInitializer operation.

andru · 2014-01-17T09:37:07Z

Agreed @ccamarat - ideally I don't see the need for a distinction either. If an initializer returns a promise then the module should add it to the stack of initializer promises, firing done when they've all resolved.

The reason it's currently implemented like this is that it requires changes to the Marionette.Callbacks object. Since this is my first contrib I didn't want to mess with a component which is being utilised in different contexts. That said, as far as I can tell Marionette.Promises could be a non-breaking replacement for Marionette.Callbacks.

If there was core support for the idea I'd happily rework it.

paulovieira · 2014-01-17T14:37:27Z

Seems like a very cool improvement for Marionette.Modules.

@andru, could you please set a jsfiddle showing a use case?

jamesplease · 2014-01-17T14:43:11Z

👍 for replacing/extending Marionette.Callbacks with this functionality. And I think it's possible to do this in a non-breaking way – you should go for it!

ccamarat · 2014-01-17T19:01:37Z

Ditto.

cobbweb · 2014-01-17T23:36:02Z

Yea this sounds ok, would be good to see if we could use Marionette.Callbacks though.

samccone · 2014-01-20T22:59:40Z

maybe get this sucker in for the 1.6 release

andru · 2014-01-21T08:59:46Z

When's the 1.6 release @samccone ? I can try and get these changes in with tests in about a week.

cobbweb · 2014-01-21T22:59:33Z

spec/javascripts/module.start.spec.js

@@ -2,14 +2,20 @@ describe("module start", function(){
  "use strict";

  describe("when starting a module", function(){
-    var MyApp, myModule, initializer;
+    var MyApp, myModule, initializer, async_initializer;


Use camelCase, asyncInitializer

jamesplease · 2014-02-25T18:11:49Z

@andru any updates?

andru · 2014-02-26T15:06:17Z

@jmeas I've unfortunately not been able to work on the project this is connected to recently. I'll be working on it again in about a week, so I should be able to update this pull request then.

dminkovsky · 2014-03-17T07:26:37Z

Promises here would be great.

An alternative method to the one proposed in the pull request would be like the one in https://github.com/domenic/chai-as-promised. There, a test runner does not advance to Test 2 until the promise returned from Test 1 is resolved or rejected. A bit externally than what's being proposed here, if I'm understanding correctly.

dmytroyarmak · 2014-03-27T08:43:04Z

I'm on it and I've almost done)
PR will be after few days.

Anachron · 2014-03-27T08:50:44Z

Weren't we trying to remove jQuery from the library dependencies? Correct me if I am wrong.

andru · 2014-03-27T08:55:42Z

Thanks @dmytroyarmak - I've had almost no free time to commit to this. If you need anything from me please just let me know.

@Anachron Is there a an option for an ES5 promises polyfil? The jQuery implementation of Promises is a particularly weird one, but I didn't want to add dependencies when a promise implementation library was already available in an existing dependency.

jamesplease · 2014-03-27T12:06:57Z

I think we should use weird jQuery Deferreds.

//cc @samccone @cobbweb @jasonLaster

jasonLaster · 2014-03-29T23:00:41Z

Closing this PR so that the discussion can move to #1069.

Added asynchronous module initializers.

7447b45

andru reviewed Nov 23, 2013
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andru mentioned this pull request Nov 23, 2013

Asynchronous module initializers to trigger a "ready" module event #772

Closed

jasonLaster reviewed Dec 29, 2013
View reviewed changes

samccone closed this Jan 15, 2014

samccone reopened this Jan 16, 2014

andru mentioned this pull request Jan 17, 2014

Discussion: Restructuring of Modules #859

Closed

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cobbweb reviewed Jan 21, 2014
View reviewed changes

jamesplease mentioned this pull request Mar 12, 2014

Allow for promises to be returned from serializeData #1004

Closed

dmytroyarmak mentioned this pull request Mar 17, 2014

Adding a done() callback to application initializers? #1019

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dmytroyarmak mentioned this pull request Mar 29, 2014

Async module initializers and finalizers #1069

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jasonLaster closed this Mar 29, 2014

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Added asynchronous module initializers. #792

Added asynchronous module initializers. #792

andru commented Nov 23, 2013

andru Nov 23, 2013

eethann commented Dec 8, 2013

jasonLaster Dec 29, 2013

samccone commented Jan 15, 2014

andru commented Jan 16, 2014

samccone commented Jan 16, 2014

andru commented Jan 16, 2014

ccamarat commented Jan 17, 2014

andru commented Jan 17, 2014

paulovieira commented Jan 17, 2014

jamesplease commented Jan 17, 2014

ccamarat commented Jan 17, 2014

cobbweb commented Jan 17, 2014

samccone commented Jan 20, 2014

andru commented Jan 21, 2014

cobbweb Jan 21, 2014

jamesplease commented Feb 25, 2014

andru commented Feb 26, 2014

dminkovsky commented Mar 17, 2014

dmytroyarmak commented Mar 27, 2014

Anachron commented Mar 27, 2014

andru commented Mar 27, 2014

jamesplease commented Mar 27, 2014

jasonLaster commented Mar 29, 2014

Added asynchronous module initializers. #792

Added asynchronous module initializers. #792

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andru commented Nov 23, 2013

_deferReady

ready

_initializerPromises

andru Nov 23, 2013

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ccamarat commented Jan 17, 2014

andru commented Jan 17, 2014

paulovieira commented Jan 17, 2014

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jamesplease commented Feb 25, 2014

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Anachron commented Mar 27, 2014

andru commented Mar 27, 2014

jamesplease commented Mar 27, 2014

jasonLaster commented Mar 29, 2014

`_deferReady`

`ready`

`_initializerPromises`