Using MobX with third-party data structures

[qwertie]

MobX supports the standard collection types Array, Map and Set. But what would happen if one tried to use a third-party data structure such as this B+ tree inside an observable object?

Internally, this data structure mutates itself in the usual way - setting its own properties, modifying internal arrays with methods like push and splice - but of course it is unaware of MobX and I wonder if this could cause any problems if it were used with, say, makeAutoObservable.

It is not documented whether makeAutoObservable recursively modifies subobjects, but I assume it does based on MobX code examples I've seen.

Whether or not this data structure is compatible with MobX, I expect MobX to have significant overhead, e.g. it will create some kind of state information for every public and internal method inside the B+ tree, even though any given application doesn't use all of those functions, and it will have to keep track of changes to the tree in detail. So, is there a way to treat the whole thing as a "black box" — to inform MobX when a prop of type BTree is read or written, but not rewire all of the internals of the data structure?

[mweststrate]

MobX will only recurse into plain data structures; class instances won't be touched, so if your B tree has a prototype it will be safe.

[qwertie]

I don't know what "be safe" means, but the goal is correct behavior. So, how do I get reactivity to work correctly? Also, BTree has a superset of the Map and Set methods. Would it be possible to piggyback on whatever MobX does for those types?

[qwertie]

P.S. it's strange that I've been reading the documentation for hours and never saw mention of a dichotomy between constructor-having and constructor-lacking objects. Where do you document all these fine details? Definitely not in the API reference, which doesn't even include parameter info.

[mweststrate]

MobX doesn't allow makeing class instances observable from the 'outside'. Introducing observability is the responsibility of the constructor, so subclassing might help you here, but that depends a lot on the library.

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On Tue, Apr 27, 2021 at 3:13 PM David Piepgrass ***@***.***> wrote: I don't know what "be safe" means, but the goal is correct behavior. So, how do I get reactivity to work correctly? Also, BTree has a superset of the Map and Set methods. Would it be possible to piggyback on whatever MobX does for those types? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2922 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAN4NBFRVVZJHJJ4NYKP66LTK3BBRANCNFSM43T6OIGQ> .

[mweststrate]

https://mobx.js.org/observable-state.html#non-convertibles

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On Tue, Apr 27, 2021 at 3:24 PM David Piepgrass ***@***.***> wrote: P.S. it's strange that I've been reading the documentation for hours and never saw mention of a dichotomy between constructor-having and constructor-lacking objects. Where do you document all these fine details? Definitely not in the API reference <https://mobx.js.org/api.html>, which doesn't even include parameter info. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2922 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAN4NBAX326OKUAF6KGM6GLTK3CLPANCNFSM43T6OIGQ> .