*code:*
var EventEmitter = require('events').EventEmitter
var groups = {}
function buildEmitters(name) {
var self = new EventEmitter
function sayWhat () {
self.emit('what')
}
self.on('what', function () {
console.log(name + ' says what')
})
function addGroup (group) {
self.on(group, function () {
console.log(name + ' was called by group, what')
})
if( ! Array.isArray(groups[group]) ) groups[group] = []
groups[group].push(self)
}
function callGroup (group) {
if (Array.isArray(groups[group]) )
groups[group].forEach(function(ee){ ee.emit(group, name) })
}
self.sayWhat = sayWhat
self.addGroup = addGroup
self.callGroup = callGroup
return self
}
var A = buildEmitters('grep')
, B = buildEmitters('cat')
, C = buildEmitters('tar')
A.addGroup('wheel')
B.addGroup('wheel')
C.addGroup('wheel')
A.sayWhat()
B.sayWhat()
C.callGroup('wheel')
Am Donnerstag, 21. März 2013 05:58:21 UTC+1 schrieb Postlethwaite:
>
> I have a little code question for you.
>
> *code:*
>
> var EventEmitter = require('events').EventEmitter
>
>
>
> function buildEmitters(name) {
>
> var self = new EventEmitter
>
> function sayWhat () {
> self.emit('what')
> }
>
> self.on('what', function () {
> console.log(name + ' says what')
> })
>
>
> function addGroup (group) {
> self.on(group, function () {
> console.log(name + ' was called by group, what')
> })
> }
>
> function callGroup (group) {
> self.emit(group, name)
> }
>
> self.sayWhat = sayWhat
> self.addGroup = addGroup
> self.callGroup = callGroup
>
> return self
>
> }
>
>
>
> var A = buildEmitters('grep')
> , B = buildEmitters('cat')
> , C = buildEmitters('tar')
>
>
> A.addGroup('wheel')
> B.addGroup('wheel')
> C.addGroup('wheel')
>
>
> A.sayWhat()
> B.sayWhat()
>
> C.callGroup('wheel')
>
>
> which outputs:
>
> grep says what
> cat says what
> tar was called by group, what
>
> I would like it to say:
>
> grep says what
> cat says what
> tar was called by group, what
> cat was called by group, what
> grep was called by group, what
>
> I know I can use the
>
> if (!(this instanceof buildEmitters)) return new buildEmitters()
> EventEmitter.call(this)
>
>
> along with the
>
> buildEmitters.prototype = new EventEmitter
>
>
> and in the addGroup method:
>
> buildEmitters.prototype.on(group, callback)
>
> and in the callGroup method:
>
> buildEmitters.prototype.emit(group)
>
>
> pattern. It works, and it's used everywhere.
>
> *problem:*
> But I am attempting to write code without inheritance and prototype calls.
> Zero.
> Just clean and simple little objects.
>
> *question:*
> Is it possible to get 'events' to propagate between the objects that *
> buildEmitters* creates? Any patterns, hacks or blatantly obvious
> workarounds that I am missing?
>
> Thanks!
>
>
>
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