not working proxyMap<K, V>() with proxyWithHistory

[Danue1]

Full Example: https://codesandbox.io/s/valtio-forked-purfbz?file=/src/App.tsx

We can follow the steps below on Full Example.

• Click "add"
• Click "add"
• Click "undo" <<- boom with "Cannot destructure property 'name' of '(0 , _valtio.useSnapshot)(...)' as it is undefined."

We can look at the source code and understand why this happens.
"deepClone" function is because it does not restore the proxy state.

valtio/src/vanilla/utils/proxyWithHistory.ts

Lines 7 to 21 in f8a1bdc

	const isObject = (x: unknown): x is object =>
	typeof x === 'object' && x !== null
	const deepClone = <T>(obj: T): T => {
	if (!isObject(obj)) {
	return obj
	}
	const baseObject: T = Array.isArray(obj)
	? []
	: Object.create(Object.getPrototypeOf(obj))
	Reflect.ownKeys(obj).forEach((key) => {
	baseObject[key as keyof T] = deepClone(obj[key as keyof T])
	})
	return baseObject
	}

It seems that this may be the design intent.
But what if we need a Map<K, V>?

1. Use Record<K, V> instead of Map<K, V>.
2. Modify proxyWithHistory to support Map<K, V>, Set.
3. (no idea)

I'd like to avoid 1 if possible.

[dai-shi]

I don't think proxyWithHistory with embedded proxy is ever supported.
So, maybe you just don't use proxyWithHistory and implement history capability somehow on your end. (I don't have any concrete ideas.)

By design, proxyWithHistory is not perfect 👉 #725 (comment)

[Danue1]

Hmm, It is possible to stack only patches using immer.js, but considering the convenience of valtio, it seems somewhat disappointing. ref.

Is there a better way?
For example, in valtio, there is an idea to provide an API that diffs only patches.

[dai-shi]

Creating patches is out of the scope of Valtio. The simplicity of Valtio design is snapshots, which cares only the result.
Though, we have a project outside to explore applying kind of patches. (I wouldn't call/consider them "patches")

• https://github.com/jotaijs/jotai-valtio
• https://github.com/dai-shi/valtio-yjs

proxyWithHistory is designed around snapshots and that's why I suggest people to create a third-party package for more capability.

[Danue1]

Thank you for introducing the project, and understanding the secret of valtio's simplicity!