What are the implications of 0.83 and removal of legacy architecture code?

[jerielng]

From my understanding 0.82 no longer allows legacy arch opt-in, and 0.83 will actually start the process of removing pieces of interop code. Could we get some insight into what this means and its implications for developers?

As a library provider, I am currently providing backwards compatibility for both architectures (i.e. RCT_NEW_ARCH_ENABLED flags, conditionals, etc.), but it sounds to me like some of that interop logic might not be available moving forward. If I'm planning to continue supporting < 0.82 for the time being, but also want to support newer versions including > 0.83, would it be too aggressive to remove the legacy architecture in anticipation of 0.83 (to ensure my library compiles with newer versions), or would that be the correct idea?

[liamjones]

and 0.83 will actually start the process of removing pieces of interop code

I'm not sure that's correct? The 0.82 blog post says:

We will keep the interop layers in the codebase for the foreseeable future. All the classes and functions that are required by the interop layers won’t be removed anytime soon. We will share further updates in the future regarding the removal of Interop Layers.

We’ve also verified that the 3P libraries that offer backward compatibility with both architectures will keep on working with 0.82 where New Architecture is the only architecture.

[liamjones]

I should also mention the blog post links to the RFC re removal of the legacy architecture which might help: react-native-community/discussions-and-proposals#929

[jerielng]

Thanks! Sorry, I think I might've initially misunderstood. What I was referring to was the announcement at this year's React Native keynote, where they said they would start removing legacy architecture classes in 0.83.

Looking back at it, it sounds like the interop layers will be here to stay, but it's just the legacy architecture code itself that will be removed? I'm assuming that means if your code is calling any interops, those would still be valid, right?

[jerielng]

That being said, I'm curious if the React Native maintainers have any guidance on when libraries could start to remove those interops? Having conditionals adds slightly more overhead in maintenance, but I'd still like to balance that with not being too aggressive in cutting out support.

[liamjones]

Looking back at it, it sounds like the interop layers will be here to stay, but it's just the legacy architecture code itself that will be removed? I'm assuming that means if your code is calling any interops, those would still be valid, right?

That's how I understand it too, yes.