Wait to call the final callback until all subtasks have returned.
Yep, that's it. As of this writing this 'library' is 17 lines of code. You can initialize it on a target callback, and then you can create subtasks of that one. When all the subtasks have completed it will call the target callback.
It supports the node convention of (err, data). If any of your subtasks return results they will be accumulated in an array. If any return an error, the target will be called immediately with the error, and the results of all further subtasks will be ignored.
should = require 'should' accumulator = require '../lib/accumulator' describe 'accumulator', -> it 'should wait for all collectors to return', (done) -> collector = accumulator done setTimeout collector(), 1 setTimeout collector(), 2 setTimeout collector(), 3 it 'should return all results', (done) -> collector = accumulator (err, results) -> should.not.exist err results.should.eql [0, 1] done() i = 0 doStuff = (cb) -> -> cb null, i++ setTimeout doStuff(collector()), 1 setTimeout doStuff(collector()), 2
Why'd you write it?
I use Async for some stuff. Async is complex. I've seen promises, but they look a little bit too low level. This is like promises, but a very special case. This happens to be the case that I find myself needing about 80% of the time, and I wanted something very simple to use, very simple to think about and maintain.
Copyright (c) 2013 Torchlight Software firstname.lastname@example.org
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.