add mstRunInAction

[xaviergonz]

• Added mstRunInAction, similar to mobx's runInAction but for MST node instances.
• Removed castFlowReturn since when a flow returns a promise what is actually returned from the flow is the resolved value. (this makes mobx and mst flow defs similar)

mstRunInAction(node, name?, thunk)

Usually used to do async/await actions without the need for superfluous actions. Not as good as flow, but has better type inference.

That being said I'm really looking forward Strongly typed iterators and generators in the roadmap for TS 3.5 to finally fix the typings for flow

[coveralls]

Coverage increased (+0.08%) to 92.442% when pulling 23c1918 on mstRunInAction into 462904d on master.

[mweststrate]

I'm not a fan of mstRunInAction. I think it encourages anti patterns, which, if needed, can be really easily solved in userland with something along the lines: .actions(self => ({ runAny(thunk) { return thunk(self) } } ). I think mstRunInAction might bless an approach that generally should be avoided. Did you have any direct use case?

[mweststrate]

The example mentioned in the docs would benefit from either using flow, or splitting in separate actions imho

[xaviergonz]

To be honest if flows were to be properly typed in TS (or if async/await were to work ok) I'd not have much of a use case. I usually skip flows in the original mobx and use runInAction after awaits exclusively for this reason (yield always returning any).

Another alternative is using anonymous actions, with private actions that are not exposed, but that's not possible unless there's some way in models to create those (which mstRunInAction would allow).

Maybe a better way to do this is to rename it to mstAction and make an example like this?

actions(self => {
  const privateAction = mstAction(self, (x: number) => { self.x = x })

  return {
    async asyncAction() {
      const x = await something()
      privateAction(x)
    }
  }
})

[jamonholmgren]

@xaviergonz Any update on this? I'm taking over MST as primary maintainer, just checking to see if you still want to pursue this.

[xaviergonz]

Sorry, feel free to close it