Open gaearon opened 5 years ago
We develop the next version of haul on next branch and disabled hot loader because it was just too hacky. We're happy to give Fast Refresh a try. Cc @zamotany who's developing Haul at the moment
@gaearon Yeah, I'm happy to chat (with pretty much whatever means of communication you prefer). Alternatively you can write me a quick overview and point me to the source code in Metro if needed.
any updates on this?
I wrote an overview of how Fast Refresh works here: https://github.com/facebook/react/issues/16604#issuecomment-528663101
There's a few implementations linked from that thread.
Since Haul uses webpack, it might make sense to join efforts with https://github.com/pmmmwh/react-refresh-webpack-plugin.
To anyone interested in the issue.
There's a common misconception that just because something is built for Webpack, it will work out of the box for React Native with Haul. 90% of the time it doesn't. Anything that's. being built for Webpack targets web and uses browser API.
From the investigation done some time ago here are the takeaways what would have to be done in order to support React Refresh in Haul. The fast refresh is terribly complex issue and it would require major changes and additions to support. As a base for investigation I did some time ago, I used https://github.com/pmmmwh/react-refresh-webpack-plugin:
New React Refresh plugin should be created for Haul with React Native specifics in mind. It would require a lot of resources to port/workaround pmmmwh/react-refresh-webpack-plugin
usage of browser specific APIs, because in Haul to support RN platform there'a a lot of tweaking and additional code that has to run in specific order. With the way pmmmwh/react-refresh-webpack-plugin
is built, this order is not kept which results in crashes.
Some tweaking in Webpack config will be necessary. For sure adding a HotModuleReplacementPlugin
. Given my experience with working with this plugin, it also assumes that the browser APIs will be present, which means we would need to workaround or hack this usage somehow.
To support HotModuleReplacementPlugin
(which is needed to support React Refresh plugin) there's a need for major refactor for the server/compiler architecture that Haul is currently using. For each platform it would need a separate Webpack Hot Middleware so essentially we would need for each platform:
And then a single proxy packager server that would proxy requests for specific platform to each platform-specific packager server. The platform-specific Webpack compiler, platform-specific server and platform-specific hot middleware together will have to be spawned in a separate process/thread.
To summarise: there are a lot of moving parts to get this working and it requires extensive/deep knowledge about how Webpack works - more specifically what parts are put into the final bundle, how the module system and Webpack logic working in the bundle and how HotModuleReplacementPlugin
itself works.
@zamotany Does this mean it will not be supplied in near future (if at all)?
Describe the feature
We've landed Fast Refresh on React Native master. You can try it if you build all Metro packages from master and replace them in
node_modules
of RNTester.Motivation
It would be nice if Haul could replace
react-hot-loader
or other techniques with Fast Refresh because:react-hot-loader
and similar tools)It likely also fixes hot reloading problems with navigation libraries because it's fully integrated with React. (Although I don't have a test case to verify that.)
It would also unify the behavior with mainline React Native.
But How?
I'd be happy to chat with someone to give an overview of how the new system works. For a 100% match in behavior we might need some new hooks from webpack, but you should be able to get reasonably close today too.