Le 21 déc. 2015 à 12:23, Joe Groff via swift-evolution
<[email protected]> a écrit :
> Some behaviors like `lazy` and `resettable` want to take control of the
> storage to manage their semantics, but many behaviors are adapters
> independent of how the underlying behavior behaves. These kinds of behavior
> are easy to compose with other behaviors and to override base class
> properties with. You could use inheritance-like syntax to indicate a
> "wrapping" behavior like this, and commandeer `super` to refer to the
> underlying property. For instance, `synchronized`:
It's unclear to me whether you can write behaviour extensions with this new
model. I'm not sure if that's really needed, but with the struct-based model,
you could.
> If you want to refer back to the containing `self`, we could support that
> too, and by treating behavior functions specially we should be able to
> maintain coherent semantics for backreferencing value types as well.
> Implementing `synchronized` with a per-object lock could look like this:
>
> var behavior synchronizedByObject<T>: T where Self: Synchronizable {
> get {
> return self.withLock { return super }
> }
> set {
> return self.withLock { return super }
> }
> }
Instead of simply writing `: T`, you could use a parameter list to give a name
to that `super`-property:
var behavior synchronizedByObject<T>(var parentProperty: T) where Self:
Synchronizable {
get {
return self.withLock { return parentProperty }
}
set {
return self.withLock { parentProperty = newValue }
}
}
--
Michel Fortin
[email protected]
https://michelf.ca
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