fix unexpected isolation

[ImSingee]

• add scope-with-reducer example
• fix isolation

This fixes #16

[dai-shi]

Hi, thanks for working on this! Can you quickly explain what was the bug? It seems that the PR diff includes both a fix and a refactor.

[ImSingee]

@dai-shi In fact, I can't figure out the real bug. I have read every code (both jotai, jotai-utils, jotai-scope), but all seem correct.

Finally, I guess that's because of the redundant createScopedAtom on the non-isolated atom, so I try to delete them (do a small refactor, mainly removing the un-need arguments and logic), and it works...

[dai-shi]

Okay, I will review the code again later.

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[dai-shi]

Hi, I updated examples/02. There, I want to have doubledAnotherCount be in sync with anotherCount.

It breaks with this PR change. However, I'm not sure if we can cover both cases.

[ImSingee]

@dai-shi In my opinion, it's the developer's duty to keep two associated atoms both isolated or unisolated.

One is isolated and another is unisolated can be treated as undefined behavior, and we should only say "do not do this thing" in the document, not try to solve the problem.

I think not creating unexpected isolation is far more than handling this edge case.

[dai-shi]

This is actually requested by users, and I think it's a requirement, not an undefined behavior. We strictly want to support, use cases like:

const countAtom = atom(0);
const anotherAtom = atom(1); // only this will be scoped
const mixedAtom = atom((get) => get(countAtom) + get(anotherAtom));

That's why the current implementation is very complicated. Maybe, it's impossible to cover all the edge cases.

If we want to isolate atoms totally, it would be much easier to implement with Provider and a React Context. We can explore such capability as a new util, but it's different from the goal of current ScopeProvider.

[ImSingee]

@dai-shi Got it!

For others, if you want to use the jotai-scope with reducer, you can use npm @singee/jotai-scope 0.4.3 ("jotai-scope": "npm:@singee/jotai-scope@0.4.3"). It's published based on this PR and can be used with reducer, but not with the above case.

I hope we can find a solution to both cases.

[yf-yang]

Fixed with #20