Add anyway version of map and parallel

[allevo]

Use mapAnyway or parallelAnyway for doing something in parallel but if some tasks fail, the others will be executed anyway. In the final callback, the first parameter is valued with all errors. For mapAnyway, the second parameter with all mapped object.
Add main test for parallelAnyway and mapAnyway.

[caolan]

Hi @allevo, I'm not sure about the name. Perhaps something like mapResumable or mapContinue or something?

[allevo]

Yes the problem is the name! Give me your preferred name for those functions.
But i have another inconvenient: async.each isn't converted. Please give me some time.

Are you interested in this pull request?
Would you prefer I pull to a non-master branch?

[caolan]

@allevo yes, I'm interested in this, it's been asked for a few times. Mostly it's a question of API and naming rather than code.

[allevo]

I've used "anyway" suffix to indicate the process goes on anyway if an error occurs.
Please tell me what name you prefer and I'll change it!

[aearly]

Another question -- would mapAnyway and parallelAnyway return null values for those tasks that fail? Error objects? Omit them?

As for naming -- how about mapMaybe or parallelMaybe? Signifies that there may be undefined results, and that you want to be able to continue.

[allevo]

Each function returns an array (or object) where the errors are. https://github.com/allevo/async/blob/master/test/test-async.js#L807 https://github.com/allevo/async/blob/master/test/test-async.js#L1097 Here you can find the test of error case.
Perhaps the error array maintain the position of the failed functions. As you like!
Now, if the only second function fails, the error array in the final callback has the first value set to the error instead of be [null, Error]. Contrariwise if there's an object, the error is an object whose values are the errors or null

[lxe]

Can't this be already accomplished with the existing methods?

async.map([1, 2, 3, 4, 5], function (name, callback) {
  fs.readFile(thing, function (err, data) {
    callback(null, {
      error: err,
      data: data
    });
  });
}, function (err, results) {
  // results[n].err  is the error
  // results[n].data is the value
});

[allevo]

Sorry for the late.
Yes you can do this but it's very horrible to see!
And you'll use a map to have only the results

[allevo]

If you don't like the interface, please tell me which you prefer! 👍
I'll apply as soon as possible

[allevo]

Is this PR blocked? I need this!

[aearly]

I like this idea, but I dislike the global collect and uncollect states. Closing this in #349. We'll think up a general solution.

[aearly]

Nevermind, got PRs mixed up.

[kmgilbert100]

+1

[gocoffeecup]

+1

[kmgilbert100]

Why hasn't this been added yet?

[allevo]

Because @caolan hasn't decided the names yet. As soon as possible, I'll resolve the conflict and repush the PR

[aearly]

I realized that this breaks one of map's guarantees -- that the results returned in the same order as their inputs in the original array. If half your tasks callback an error, you'll get a results array that is half the size of the original array. It also is a bit of a convention break to return an array of errors (rather than a single Error object) as the first arg to a callback.

We're going to go back to the drawing board with #942