Why not use event callbacks?

Its an interesting choice how drivers work in Cycle. I’m curious why you didn’t stick with the whole “callback” style of registering events. This would make it easier to build drivers and to integrate with other libraries.

I think this example maintains the spirit of Cycle, but allows you to use React (and React Native) and entirely deals away with the the issue of isolation (isolateSink and isolateSource).

import {stream, scan} from 'flyd'
import lift from 'flyd/module/lift'
import h from 'react-hypersrcipt'

const counter = (props$) => {
  const action$ = stream()
  const state$ = scan(add, 0, action$)
  const inc = () => action$(+1)
  const dec = () => action$(-1)
  const view = (props, state) => {
    return h('div', props, [
      h('button', {onClick: dec}, '-'),
      h('span', state),
      h('button', {onClick: inc}, '+')
    ])
  }
  return {
    html$: list(view, props$, state$),
    count$: state$
  }
}

The way the current DOM driver works (binding actions before creating the DOM), makes me think that they’re may be certain dynamic interfaces that couldnt be created.

Anyways, I’m curious about your thoughs on this decision.

[gaearon]

I just don’t understand how to you connect drivers.DOM.select(‘input’).events(‘click’) to the input thats eventually returned to the DOM driver. It seems pretty challenging or littered with mutations. Take React for example – how does the event handler get injected into the vdom before its rendered?

I’m not a Cycle expert but I wanted to make clear that even React does not actually “inject handlers into vdom”. It is usually bad for performance to attach many event handlers, so under the hood React just registers component handlers in a map by the internal component ID, and only sets up a single event handler at the root of React hierarchy. This is similar to the event delegation approach that has long been used in Backbone and jQuery. I think in some cases React might actually subscribe to the node in question (depends on the event and browser quirks) but more often I think (it’s best if you verify!) it subscribes to the root node.

[staltz]

Nowadays Cycle DOM also does event delegation.