Cool, yeah, the reveal pattern would indeed be a good way to guard
against unwanted/unexpected cancels.
```js
class Cancel {
constructor(executor) {
this._requested = false
executor(() => this._requested = true)
}
get requested() {return this._requested}
throw() { throw new CancelError() }
}
let cancel = new Cancel(function(cancel) {
cancelButton.onclick = cancel
})
```
What would be the recommended way of keeping the internal state
private? With a WeakMap?
On Mon, Jan 4, 2016 at 1:01 PM, Kevin Smith <zenpars...@gmail.com> wrote:
>> Since checking `promise.state` is synchronous, we may as well just
>> write a synchronous Cancel class instead:
>
>
> Right - see upthread. You do need some kind of callback method, though,
> like `whenCancelled(callback)`.
>
>>
>> class Cancel {
>> constructor() { this.requested = false }
>> request() { this.requested = true }
>> throw() { throw new CancelError() }
>> }
>
>
> We need to separate the capability to "read" the cancellation request from
> the ability to request the cancellation. That's why in .NET you have
> CancellationTokenSource and CancellationToken. But for JS, we should
> probably use the revealing constructor pattern instead (discussed upthread):
>
> let token = new CancelToken(cancel => { ... });
>
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