Cancelable promises

Kevin Smith zenparsing at
Thu Feb 26 23:31:44 PST 2015

The discussion on that github issue surrounding promise subclassing makes
my head spin, especially when it comes to working out how cancelation is
supposed to flow through a graph of promise dependencies.  We should be
wary of adding complexity to the core.

The simple way to view the situation is to say that promises are simply
transparent containers for asynchronous values. Control capabilities should
therefore be represented by a separate abstraction. This will help keep
complexity at the edges.

Has any library experimented with the cancelation token approach yet?
On Feb 27, 2015 1:46 AM, "Anne van Kesteren" <annevk at> wrote:

> As a heads up, there's some debate around the fetch() API how exactly
> request termination should work and how that affects promises:
> The WebRTC WG has also been discussing canceling in the context of
> terminating a request for permission from the user. I think they
> decided to postpone for now until there's a bit more progress on what
> cancelable promises means, but I would not expect everyone to wait
> forever.
> --
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