Diamond problem with subscribers about effector

[zmitry]

I guess for this particular case we could add some helper which uses subscribers field

function watchGreedy(store, cb) {
store.subscribers.entries.forEach(el=>{
  el.watch(cb);
})
}

[zerobias]

as both cases are pretty valid, we need to handle each one
as watch is going to become a thing on its own, we could add configuration during creation
for example

this code will be called as often as possible

watch(lastEvent, {
  greedy: true,
  async handler(data) {
    sendAnalytics(data)
  },
})

and this one will be called only with last relevant update

watch(lastEvent, {
  greedy: false,
  async handler(data) {
    render(data)
  },
})

what do you think?

[dundich]

maybe

greedy(lastEvent,    //or tick(lastEvent,  or last(..., or every(.....
  async handler(data) {
    sendAnalytics(data)
  }
)

[zerobias]

there could be another options, e.g skipFirst: true for skipping first immediately appeared update

[dundich]

Can do like in Rxjs?

https://www.learnrxjs.io/operators/filtering/skip.html

import {  skip,filter,tap,take,takeUntil,finalize, map ....  } from 'foo-magic/operators';

const clickButton = createEvent()

const clickStore = createStore({e:'none'}).on(clickButton, (e) => {e:'click'})

const cancel$ = createEvent();

const lastStore$  = clickStore    // as event emitter (state, events ....   )
.pipe(  // magic combine
  takeUntil(cancel$),  // listen until no cancel event
  skip(1),  // skip ...for skipping first
  debounceTime(1000), // button-events thrash filter
  tap((state) => console.log(state)), 
  map((state) => {...state,  say: "УРА!"   }),
  tap((c) => console.log(c.say)),
  finalize(() => console.log("THE END"))
).subscribe(); // for example

// bla-bla  
for(int i=0; i<10; i++) clickButton();

clickStore.watch((e)=> console.log('SPAM!'); )
lastStore$.watch((e)=> console.log(e.say)) // УРА!

[everdimension]

I don't see how clickButton and closeModal can be invoked synchronously.
I mean, they can, but it probably makes no sense.

If they are invoked at different points in time, then analytics will get all expected results.

So perhaps it doesn't make sense for isolated atomic actions to be invoked synchronously? And in the rare cases where it does, it might be okay to only get notified about latest state?

[artalar]

@everdimension clickButton trigger closeModal synchronously by forward.
My example - is just an example, not from my product code, but it is a good illustration for a diamond problem for subscribers.
Library calculation is accumulative for subscribers, what is mean under the hood all store and events dependencies (graph) calculations "flatify" and subscribers receive only last updates (even if there were several).

[zerobias]

implemented as sample for making updates non-greedy