Since checking `promise.state` is synchronous, we may as well just
write a synchronous Cancel class instead:
```js
class CancelError extends Error { /* ... */ }
class Cancel {
constructor() { this.requested = false }
request() { this.requested = true }
throw() { throw new CancelError() }
}
async function f(cancel) {
await cheapOperation(cancel) // some other function might call
cancel.request() while we await here.
if (!cancel.requested)
await expensiveOperation(cancel)
}
let cancel = new Cancel
cancelButton.onclick = () => cancel.request()
f(cancel)
```
Wouldn't this be better than using a Promise if we are relying on a
synchronous check anyways?
On Mon, Jan 4, 2016 at 12:30 PM, Kevin Smith <[email protected]> wrote:
>> We have pretty sound cancellation semantics in bluebird 3.
>
>
> Cool, I'm aware that cancellable promises have been explored in depth. I'd
> prefer to keep this thread focused on cancellation tokens though, and avoid
> comparisons.
>
>
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>
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