Actually I’ve done my homework and I can tell you that it will be possible if
SE-0095 is accepted.
Here is how to abuse this:
protocol A {}
protocol B {}
typealias AB = protocol<A, B>
protocol C: AB {}
That renamed will be:
protocol A {}
protocol B {}
typealias AB = Any<A, B>
protocol C: AB {}
Do we need this or should we ban this?
I’m not sure, because we can’t use `Any<…>` directly on a protocol. Using a
typealias was a workaround that worked.
If we keep it that way, it will be fine with my proposal of disallowing
redundant types `Any<…>` could create:
https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160516/018280.html
It looks strange if you can only use typealias for that. If we change that so
we could use `Any<…>` directly one would ask why can’t we use `Any<UIView>` on
protocols? This is a different story, because we never talked if we can build
protocols with type requirement.
--
Adrian Zubarev
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Am 20. Mai 2016 bei 15:02:35, Adrian Zubarev ([email protected])
schrieb:
Can we use `Any<…>` for protocol conformance like this:
protocol A: Any<class> {} <— this makes a little sense, but I’d rather write
protocol A: class {} instead
protocol B: Any<UIView, SomeProtocol> <— this is confusing. One could argue we
could apply B only on any UIView subclass which conforms to SomeProtocol, but
why can’t we do also this: protocol C: Any<UIView>
One downside here is that `Any<UIView> == UIView` and should be banned because
its redundant.
We cannot write something like this:
protocol C: UIView
Or can we?
I’d propose we should ban this in Swift 3.
This implies that `typealias AnyObject = Any<class>` won’t work anymore on
protocols. This is a breaking change.
I’d write a small proposal as another follow up to SE-0095 if my thoughts are
right.
--
Adrian Zubarev
Sent with Airmail
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