Much simpler!
PR here: https://github.com/elixir-lang/elixir/pull/11101
On Thursday, July 1, 2021 at 11:06:21 AM UTC-7 José Valim wrote:
> Instead of creating a new struct, which would require changing many
> modules, I would build a regular Task and then send a message to myself in
> the form {ref, result}. :)
>
> On Thu, Jul 1, 2021 at 7:50 PM Aaron Ross <[email protected]> wrote:
>
>> I put together a PR here: https://github.com/superhawk610/elixir/pull/1
>>
>> I'd love to hear any feedback on the approach and implementation before
>> submitting to the official repo.
>>
>> Thanks in advance!
>>
>> On Thursday, July 1, 2021 at 12:33:57 AM UTC-7 José Valim wrote:
>>
>>> It sounds good to me. A small but likely welcome change. A PR to further
>>> explore this is welcome!
>>>
>>> On Thu, Jul 1, 2021 at 12:26 AM Aaron Ross <[email protected]> wrote:
>>>
>>>> +1
>>>>
>>>> I've encountered this in a similar context - I have one overall task
>>>> that will spawn some number of data fetching tasks, but in some cases I
>>>> know that the data fetch call will return no results so I stub the task
>>>> with `Task.async(fn -> {:ok, []} end)`. The proposed `Task.completed/1`
>>>> would be a great, more semantic replacement and has the benefit of not
>>>> spawning an unneeded process.
>>>>
>>>> On Wednesday, June 30, 2021 at 3:22:07 PM UTC-7 Luke Bakken wrote:
>>>>
>>>>> ## Background
>>>>>
>>>>> I have an enumerable over which I fold and call Task.async based on
>>>>> the data in the enumerable. I then Task.yield_many over the list of
>>>>> tasks,
>>>>> and use Enum.zip to correlate the original enumerable with the results.
>>>>>
>>>>> I have a case where, during the fold I find that an entry is invalid
>>>>> for running Task.async. It would be convenient to create an "already
>>>>> completed" Task that contains an error result. For now, I'm still using
>>>>> Task.async to basically return an :error tuple, which of course starts
>>>>> and
>>>>> links a process.
>>>>>
>>>>> Of course, I could work around this by using maps, etc.
>>>>>
>>>>> I tried using %Task{} to create a "dummy" but calling Task.yield_many
>>>>> with such an entry always blocks until the timeout.
>>>>>
>>>>> ## Proposal
>>>>>
>>>>> Add Task.completed/1 that creates an "already completed" Task that can
>>>>> then be awaited / yielded to return the result used when completed/1 was
>>>>> called:
>>>>>
>>>>> ```elixir
>>>>> task = Task.completed({:error, :boom})
>>>>> ```
>>>>>
>>>>> Awaiting or yielding on such a task returns the result immediately
>>>>> without invoking a process.
>>>>>
>>>>> ## Other
>>>>>
>>>>> .NET has the following to achieve this behavior, for instance:
>>>>>
>>>>>
>>>>> https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.task.completedtask?view=net-5.0
>>>>>
>>>>>
>>>>> https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.task.fromresult?view=net-5.0
>>>>>
>>>>> Thanks for your consideration! If approved I would gladly implement
>>>>> this.
>>>>> Luke
>>>>>
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>>>>
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> To view this discussion on the web visit
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