In case we discuss this feature not for just value types but for classes
also - will such AutoEquatable allows to implement protocol manually?
Now we can have:
func == (lhs: A, rhs: A) -> Bool { return true }
class A: Hashable { var hashValue: Int { return 100 } }
class B: A { override var hashValue: Int { return 200 } }
So, if we'll have
class A: AutoHashable { }
or
class A: deriving Hashable { }
will we be able to have:
class B: A { override var hashValue: Int { return 200 } }
?
(The same question was for `deriving` proposal)
Please note that we probably don't want/have no rights to modify the
definition of class A.
There is no such question for auto-derived Hashable in case of simple
conformance as we do now `class A: Hashable`.
On 30.05.2016 23:45, David Sweeris wrote:
What about declaring the requirements for auto-conformance in a sub-protocol?
@auto protocol AutoEquatable : Equatable {
//"syntax" for how to conform to Equatable
}
struct Foo : AutoEquatable {} //the compiler automatically synthesizes
everything
struct Bar : Equatable {} //you manually conform
It would be a compiler error to conform to an `@auto` protocol if the compiler couldn't
apply the provided "syntax" to the conforming type.
(I have no clue what this "syntax" could be, other than some expansion of
generics and/or a macro system)
Anyway, does that help? It satisfies both the "explicit conformance" crowd and the "no new
keywords" (at least at the "call" site) crowd.
- Dave Sweeris
On May 30, 2016, at 15:26, Vladimir.S via swift-evolution
<swift-evolution@swift.org> wrote:
I see these two groups: both wants explicit conformance to protocols, but first
thinks that current syntax is enough (`: Equatable`) and second thinks we
should introduce new keyword `deriving` for this(`: deriving Equatable`). I see
no opinions(except the one opinion in proposal itself) to automatically
deriving without explicit decoration.
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