[API Addition] bufferUnderCondition
semmel opened this issue · comments
What do you think of such a bufferUnderCondition-like function?
It buffers source stream values when the condition is truthy. When the condition is false or the condition has ended, any accumulated values are flushed and subsequent source values are let passed. The resulting stream ends when the both the condition and the source stream have ended.
As marble diagrams:
/* c: condition (t -is true, f means false), s: source, r: result
*
* time: 200 400 600 800 1000
* c: t-----------f-----------t-----------f-----------t-----------f<end>
* s: ---0--1--2----3-----4-----5678-----------9----------10<end>
* r: -----------0123-----4-------------5678---9-----------------10<end>
*
* c: ---t----<end>
* s: x---x--x--x---x--<end>
* r: x--------xxx--x--<end>
*
* c: ---t--------------<end>
* s: x---x-y-z<end>
* r: x-----------------xyz<end>
*/
I could not figure a way to do it simply with the existing API.
My implementation is goes along Bacon.mergeAll(source, condition).withStateMachine. However a PR is blocked because I cannot get the tests running, partly because of #727.
Do you think it is worth pursuing a PR?
How about holdWhen?
Hmm. holdWhen seems to be the solution.
But I was under the inpression, that as .takeWhile and .takeUntil it would work only once.
I now see that it does not, except here I cannot make it work:
var propBus = new Bacon.Bus();
var valve = propBus.toProperty(true);
var stream = Bacon.repeatedly(2000, [0, 1, 2, 3, 4, 5])
.flatMapConcat( v => Bacon.once(v).holdWhen(valve) );
var unsub = stream.onValue(console.log.bind(console));
// ... let some time pass to allow for buffering
propBus.push(false);
// -> 0 1 2 3 4 5 0
propBus.push(true);
// -> 1 2 3 4 it continues to emit values no matter what the valve is !Sorry was on mobile. This might be the problem: https://github.com/baconjs/bacon.js/wiki/FAQ#why-isnt-my-property-updated
Yes, valve needs to be a "hot" (or "eager") observable! It works now.
I already have a utility function eagerUntil for that purpose
Bacon.Property.prototype.eagerUntil = function(observable){
this.takeUntil(observable).onValue(function(){});
return this;
};
... but I always forget to attach it to my properties!
😥
Thank you very much!