Alternative for join patterns

[xgrommx]

Hello @benlesh

In baconjs and old version of rx we have feature like join patterns. But how can I emulate it in current version of Rx?

Example with bacon

const Bacon = require('baconjs');

var chopsticks = [new Bacon.Bus(), new Bacon.Bus(), new Bacon.Bus()]
var hungry     = [new Bacon.Bus(), new Bacon.Bus(), new Bacon.Bus()]

var eat = function(i) {
  return function() {
    setTimeout(function() {
      console.log('done!')
      chopsticks[i].push({})
      chopsticks[(i+1) % 3].push({})
    }, 1000);
    return 'philosopher ' + i + ' eating'
  }
}

var dining = Bacon.when(
  [hungry[0], chopsticks[0], chopsticks[1]],  eat(0),
  [hungry[1], chopsticks[1], chopsticks[2]],  eat(1),
  [hungry[2], chopsticks[2], chopsticks[0]],  eat(2))

dining.log()

chopsticks[0].push({}); 
chopsticks[1].push({}); 
chopsticks[2].push({})

for (var i = 0; i < 3; i++) {
  hungry[0].push({}); 
  hungry[1].push({}); 
  hungry[2].push({})
}

Output

// philosopher 0 eating
// done!
// philosopher 2 eating
// done!
// philosopher 1 eating
// done!
// philosopher 0 eating
// done!
// philosopher 2 eating
// done!
// philosopher 1 eating
// done!
// philosopher 0 eating
// done!
// philosopher 2 eating
// done!
// philosopher 1 eating
// done!

Old version of Rx

const Rx = require('rx');

var chopsticks = [new Rx.Subject(), new Rx.Subject(), new Rx.Subject()]
var hungry     = [new Rx.Subject(), new Rx.Subject(), new Rx.Subject()]

var eat = function(i) {
  return function() {
    setTimeout(function() {
      console.log('done!')
      chopsticks[i].onNext({})
      chopsticks[(i+1) % 3].onNext({})
    }, 1000);
    return 'philosopher ' + i + ' eating'
  }
}

var dining = Rx.Observable.when(
  hungry[0].and(chopsticks[0]).and(chopsticks[1]).thenDo(eat(0)),
  hungry[1].and(chopsticks[1]).and(chopsticks[2]).thenDo(eat(1)),
  hungry[2].and(chopsticks[2]).and(chopsticks[0]).thenDo(eat(2))
)

dining.subscribe(x => console.log(x));

chopsticks[0].onNext({}); 
chopsticks[1].onNext({}); 
chopsticks[2].onNext({})

for (var i = 0; i < 3; i++) {
  hungry[0].onNext({}); 
  hungry[1].onNext({}); 
  hungry[2].onNext({})
}

Output

// philosopher 0 eating
// done!
// philosopher 2 eating
// done!
// philosopher 1 eating
// done!
// philosopher 0 eating
// done!
// philosopher 2 eating
// done!
// philosopher 1 eating
// done!
// philosopher 0 eating
// done!
// philosopher 2 eating
// done!
// philosopher 1 eating
// done!

also probably will be helpful to use live example
https://codesandbox.io/s/elastic-khayyam-wxh62

[xgrommx]

@benlesh Are u here?)

[benlesh]

I am here, I'm just sort of the waiting for the community to comment on the desire for this feature. It's been brought up before as something we might want to add back into the library, but never gained traction.