[swift-users] Protocol composition results in EXC_BAD_ACCESS

Zhao Xin owenzx at gmail.com
Mon Apr 3 10:58:53 CDT 2017


Why not making State as a class? EffectiveState should be subclass of State.

Zhaoxin

On Mon, Apr 3, 2017 at 11:08 PM, Rudolf Adamkovič via swift-users <
swift-users at swift.org> wrote:

> On 3 Apr 2017, at 16:48, Adrian Zubarev <adrian.zubarev at devandartist.com>
> wrote:
>
> Why do you cast against an existential in first place?
>
>
> To avoid force-unwrap at the end here:
>
> class Store {
>
>     var state: State
>
>     // ...
>
>     func processScheduledActions() {
>
>         guard var effectfulState = state as? Effectful else {
>             return
>         }
>
>         while let actions = effectfulState.scheduledActions.flush() {
>             for action in actions {
>                 delegate?.store(self, didRequest: action)
>             }
>         }
>
>         state = effectfulState as! State
>
>
>     }
>
> }
>
> Thank you!
>
> R+
>
>
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>
>
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