To "streamify" a map of callbacks

Hi guys,

I was doing a facade on a legacy API where a map of callback is passed in as an arg like:

const myStupidListeners = {
    aHappened: e => {},
    bHappened: e => {},
    cHappened: e => {}
}

invokeLegacyAPI("start", myStupidListeners)

I was trying to wrap this API to multiple event streams using bacon, so for each xHappened callback, an event stream shall be created.

But however I just can’t spin my head around how to “streamify” those callbacks using factory functions provided by Bacon, at best I’m thinking of kicking start a Bus for each callbacks and pushing events to that bus in those callbacks.

Am I missing somehing form the doc and is there a better way to do this?

[philipnilsson]

Probably a Bus is the easiest solution. There are other options but since you have three callbacks you want to pass simultaneously it’s a bit trickier.

const onA = new Bacon.Bus();
const onB = new Bacon.Bus();
const onC = new Bacon.Bus();

const myStupidListeners = {
    aHappened: ev => onA.push(ev),
    bHappened: ev => onB.push(ev),
    cHappened: ev => onC.push(ev),
};

invokeLegacyAPI("start", myStupidListeners);

[raimohanska]

Optionally you can

allEvents = B.fromBinder(function(sink) { invokeLegacyAPI({a: sink, b: sink, c: sink}) })

This ways you’ll get all events into one stream. Then you need to split it into three by applying different filters. Note that you could also can tag your data like

allEvents = B.fromBinder(function(sink) { invokeLegacyAPI({
  a: function(a) { sink ({a: a}) }, 
  b: function(b) { sink ({b: b}) }, 
  c: function(b) { sink ({c: c}) }
})})

So that you allEvents stream will output stuff like

{a: "value from event a" }
{c: "something else from c"}

The Bus approach seems more approachable to me.