Persist Nested Subscriptions Through Hot Reload

[dsgkirkby]

This resolves #670.
This likely also resolves #636 but I encounter errors installing the linked repo on my machine.

Cause Of Issue

When a connected component hot reloads, it unsubscribes and then resubscribes to store updates. As part of unsubscription, all child listeners (also referred to as nestedSubs) are removed. For child components that also hot-reload, this is fine, as they will resubscribe during the hot reload. However, if any of the hot reloading parent's descendants are connected but do not hot reload, they are never resubscribed to store updates.

Solution

To resolve this, we persist the previous component's listeners to the reloaded version of the component, so that descendants that did not reload are still subscribed properly to store updates.

Downsides

This does mean that the old versions of hot reloaded components are still subscribed, but when they unmount as part of the reload, their selector.shouldComponentUpdate, selector.run, and notifyNestedSubs are all set to no-ops, making their onStateChange always a no-op itself.

[markerikson]

Sweet, thanks! We'll definitely want @jimbolla to take a look at this, and I'll try to find time to look over it myself as well.

[jimbolla]

At first glance it makes sense, but I'll have to think awhile about any foreseeable issues.

[jimbolla]

At any rate, any issues would only affect hot-reloading, which is currently broken, so this is almost certainly an improvement.

[GeKorm]

Is something blocking this? Is there anything we can do to help?

[adkasp]

it would make a life much easier for many devs, please pull

[jimbolla]

I think this is OK to merge.

[timdorr]

Cool. Here we go...

[dsgkirkby]

Thanks guys!

[3upzorz]

Any idea when this will be published?

[olegstepura]

Hi!

This PR should fix an issue #636 which makes our work very unconfortable due to hot reload issues. Personally I tried to downgrade to latest v4 as a workaround, but this broke rounting with react-router v4, so it was not an option for me.

I think I will speak for many developers waiting if I'll kindly ask you to please release this fix as soon as possible.

Thaтks a lot!

[timdorr]

OK, pushed out 5.0.6.

[pugnascotia]

I ran into this just the other day, so awesome to get it fixed! Thanks everyone!

[olegstepura]

This seem to fix #636