Handle circular dependencies about systemjs-hmr

[alexisvincent]

Pushed and published to npm

[alexisvincent]

Thanks for the issue. I can't look at it just yet, I'm swamped with deadlines. But will check this out on the weekend.

[alexisvincent]

Can you be more specific? It would be really helpful to see an example dependency tree.

[frederikschubert]

I will try to come up with a minimal example and ping you here!

[alexisvincent]

Any progress on this?

[frederikschubert]

I am currently occupied with my studies but will post an example on Friday.

[alexisvincent]

Great :)

On Wed, 02 Nov 2016 at 23:26 Frederik Schubert [email protected]
wrote:

I am currently occupied with my studies but will post an example on Friday.

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[frederikschubert]

It is really difficult to come up with a minimal reproducible example for this issue. This error appears "sometimes" in our angular 2 projects. I suspect that the error is connected to how the decorators are evaluated.
One possible fix would be to reimport the modules in the order in which they were loaded the first time. As far as I understood from the code, the order of the reimports is decided by the order of Object.keys.
Sorry that I cannot come up with something more helpful yet.

[alexisvincent]

I need to have a good look at how this hot reloader works. I think this codebase can be greatly simplified. But I may be wrong. I'm in the process of refractoring and adding comments. So I'll be in a better place to look at this later this week. SystemJS handles circular deps according to the spec. And when I take a look at this I'm hoping it's as simple as recursively deleting modules upwards and then reimporting the root and relying on SystemJS for the rest

[frederikschubert]

Yes that would have been my approach as well. Currently the modules are deleted and reimported manually by the plugin.

The manual reimport is needed to call the reload hook of the deleted modules. See here

[alexisvincent]

Oh I see. Checkout issue #2. Won't need that reload logic anymore

[frederikschubert]

Great!

[alexisvincent]

See #2 I pushed a rewrite of the reloader, with new unload and state hydration mechanisms. Should fix your issue.

[frederikschubert]

The rewrite looks good! I will give it a try as soon as I can and report my results here.

[alexisvincent]

Awesome, if you haven't already read the rewrite, I've added extensive documentation (as in more documentation then code I think), in the next.js file. Should be very clear how it works, I want it to be super simple to contribute.

[frederikschubert]

Yes I read through it. It is much easier to comprehend now! 👍

[alexisvincent]

Cool cool 👍. The README has been updated to explain how this works.

[frederikschubert]

I get the same error as #5. Using the version that is in master.
Seems like I was still using the old version.

[alexisvincent]

Oh, you need to import systemjs-hmr/dist/next.js

[frederikschubert]

Alright. Now I get this error when the System.normalize hook is called during reload:

TypeError: this.has is not a function
    at SystemJSLoader.coreResolve (http://localhost:3000/jspm_packages/system.src.js:1730:12)
    at SystemJSLoader.<anonymous> (http://localhost:3000/jspm_packages/system.src.js:1752:32)
    at http://localhost:3000/jspm_packages/system.src.js:2546:36

[alexisvincent]

Hmm. How are you testing this?

[frederikschubert]

I patched the systemjs-hot-reloader to use the new API. Basically I just removed the catch from here.
I also tried to do it via the console but I get the same error.

[alexisvincent]

How far does it get in the reload process

[frederikschubert]

The error occurs during the normalization. It seems that the prototype patching is not working correctly. The this in this function has not the right prototype chain. So the call to this.has fails here.

I should also add that I am using plugin-typescript but that should not be a problem I guess.

[frederikschubert]

I cloned this repo and tried the test and get the same error. Which systemjs version are you using?
I am using SystemJS v0.19.40.

I inlined the System.has function and then the hot reload works. In the end reloader.loadCache.clear(); throws an error because the loadCacheis undefined.

[frederikschubert]

I found a fix and will make a PR. #7

[alexisvincent]

Thanks! I also forgot, when using _System you need to _System.normalize(System, "someModule")

[alexisvincent]

Do your circular reps work now.

[frederikschubert]

Now I get this error when the modulename is normalized:

TypeError: CreateListFromArrayLike called on non-object
    at eval (http://localhost:3000/jspm_packages/github/alexisvincent/systemjs-hmr@master/dist/next.js:200:50)

[alexisvincent]

Sorry. Pushing a fix

[frederikschubert]

Great! Now it works!

[alexisvincent]

Awesome :) Thoughts on the new state hydration/ unload api?

[frederikschubert]

I like it! I am not sure about the @hot module name but I can't come up with something better. :)

[alexisvincent]

If you come up with a better name let me know :) Do you have an opinion on the exporting state vs private persistent object state hydration techniques?

[frederikschubert]

I like the current API with the exported state. This gives the developer the freedom to implement the state re-hydration any way he/she likes.

[alexisvincent]

Cool thanks for the input.