Q.all不调用任务 [英] Q.all doesn't call tasks

问题描述

所以我有这个CoffeeScript（简化为专注于真正的问题）

So I have this CoffeeScript (simplified to focus on the real problem)

Q = require 'q'
events = require 'events'

class SomeObj extends events.EventEmitter

  constructor: () ->
    setTimeout () =>
      @emit 'done'
    , 3000


class SomeObj2 extends events.EventEmitter

  constructor: () ->
    setTimeout () =>
      @emit 'done'
    , 50000

class Main

  someObj1: null
  someObj2: null
  constructor: () ->
    Q.all([
      => @task1(),
      => @task2()])
    .then (results)->
      console.log 'results'
      console.log results
    .catch((error)->
      console.log 'error'
      console.log error
    )

  task1: () ->
    console.log 'task1 started'
    defer = Q.defer()
    @someObj = new SomeObj()

    @someObj.on 'done', (err, data) =>
      console.log 'task1 done'
      defer.resolve data

    return defer.promise

  task2: () ->
    console.log 'task2 started'
    defer = Q.defer()
    @someObj2 = new SomeObj2()

    @someObj2.on 'done', (err, data) =>
      console.log 'task2 done'
      defer.resolve data

    return defer.promise


main = new Main()

输出为：

results
[ [Function], [Function] ]

Main :: constructor ，回调 @ task1 和 @ task2 似乎没有得到调用。所以要确定这一点，我已经添加 console.log 在他们的顶部。

In Main::constructor, the callbacks @task1 and @task2 doesn't seem to get called. So to be sure about this, I've had added console.log at the top of both of them. And as they don't get printed out, I can be sure they're not called.

为了测试，我替换了这个块

For testing purposes, I replaced this block

  constructor: () ->
    Q.all([
      => @task1(),
      => @task2()])
    .then (results)->
      console.log 'results'
      console.log results
    .catch((error)->
      console.log 'error'
      console.log error
    )

此区块

  constructor: () ->
    Q.fcall () => @task1()
    .then ()  => @task2()
    .then (results)->
      console.log 'results'
      console.log results
    .catch((error)->
      console.log 'error'
      console.log error
    )

这实际上是预期的，但它不是我想要的。目标是并行启动task1和2。

and this actually works as espected, but it's not what I want. The goal is to start task1 and 2 in parallel.

注意：在任务中，我想能够使用 @ 主要

Side note: Inside the tasks, I would like to be able to use @ for member variables of Main

有什么问题？

推荐答案

Q.all helper 期望一个数组或promise来解析，而不是一个函数数组。这意味着如果你想使用 Q.all ，你应该自己调用所有的任务。

Q.all helper expects an array or promises to resolve, not an array of functions. It means that you should call all your tasks yourself if you want to use Q.all.

，删除匿名函数包装将会做到：

In your example, removing anonymous function wrappings will do the trick:

constructor: () ->
  Q.all([
    @task1()
    @task2()
  ]).then (results) ->
    // Success
  .catch (error) ->
    // Error

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