Extension of Value class

[malliaridis]

Background

With the usage of Value it is possible to avoid direct dependency on coroutines / Reaktive. However, Value comes with some limitations since the implementation is not as extensive as coroutines or Reaktive.

One of the limitations I have faced so far is the combination of multiple Values in order to get a single observable. This leads either to a custom function that replicates the basic idea of coroutine's combine or Reaktive's combineLatest function, or introduce direct dependency to coroutines or Reaktive by replacing Value with Flow or Observable.

Another extension function I had to add to my projects is the conversion of Store.states to Value in order to consume state updates from MVIKotlin in Decompose. This might be a very "specific" library use case, but then I started wondering if Value has to be part of Decompose and is not just a Decompose extension library or internal class.

With that said, I think that it is not necessary to remove Value or limit its scope, but a few more operations might come in handy.

Discussion Topic

I would like to discuss and maybe collect additional ideas for extending the Value class if that makes sense.

One extension The extension I had in mind so far is a combine function that allows merging multiple Value instance into one. Even this extension might be not necessary if there are dependency-specific extensions (like converting Flow to Value or Observable to Value) where the merging can happen prior to the conversion to Value with the library-specific implementation.

[arkivanov]

Thanks for raising! Unfortunately, adding more operators for Value is very undesired. Because it's definitely not good for Decompose to open doors to become yet another reactive library. Also because Value allows reading the current value at any time and it is now thread safe, adding operators like combine would be pretty difficult.

It is advised (and you also mentioned this) to use Flow or Observable, perform all necessary transformations, and lastly convert to Value. So yeah, we can think about adding two more modules with coroutines and Reaktive extensions respectively.

As of extension for MVIKotlin Store, ideally this should be a separate library, but I can't afford one more. I would support if someone wants to create such a library, and we could even add it to MVIKotlin docs.

[malliaridis]

Thanks for the response and clarification. I think its important to be aware of this and decide early in a project which approach to follow. 🙂