How can I pipe one emitter to another? about kefir HOT 4 CLOSED

In Bacon.js there is Bus which is like Kefir's emitter, but you also can .plug streams to it. In Kefir I decided to split Bus functionality to two objects — emitter and pool. There is no docs for pool yet, but it basically .plug part of Bacon's Bus, except the method called .add.

var p = Kefir.pool();
var e = Kefir.emitter();
p.add(e);
p.log();
e.emit(1);

> [pool] <value> 1

But now, when you asking, I am not still sure it was a good idea to split Bus functionality. Maybe we should add .plug method to emitter, what do you think?

from kefir.

I think a .plug method on emitter would be nice.

Here is an example of what I would like to be able to do:

var Kefir = require('kefir'),
    service = require('service')(), // a kefir emitter for data from a given service
    processInput,
    processOutput,
    output;

processInput = Kefir.emitter();
processOutput = processInput.map(
  function (x) {
    // do some transformation
    return x + 1;
  });

output = Kefir.emitter
  .log('output');

// take output of service  send it to the inputProcess
// then take the outputProcess
// and send it to an output
service.plug(processInput)
processOutput.plug(output);

It would also be nice to be able to describe a process in a contained way. Something similar to nodes duplex stream. For example:

var process = Duplex(processInput, processOutput);

process.log();

process.emit(1); // 2
process.emit(3); // 4
process.emit(5); // 6

That way plugging the top example could be simplified to:

service.plug(process).plug(ouput);

from kefir.

Looking at your example, it seems like you misunderstand of how .plug works (in Bacon's Bus). When you call A.plug(B) you force A to listen to B and repeat events from it, not other way round.

Also it seems like you expose some output from service (i.e. you send data from service to it's user), in this case I would expose not emitter, but just some stream (which may be an emitter or not) or a property. Then I would transform that stream without using any emitters, like that:

output = service.map(
  function (x) {
    // do some transformation
    return x + 1;
  });
output.log('output');

But, I think, emitter with .plug method (i.e. Bacon's bus) is the best choice to expose as an API from a service when you want to give to users an opportunity to send some data to your service.

Maybe I'll just add Bus to Kefir, leaving emitter as it is. I will think about it.

from kefir.

As for version 0.2.8 Kefir now has .bus(). I am closing this issue for now, please feel free to reopen it if you have further questions.

from kefir.