I didn't see this in the similar questions, so I think this is unique. I have a protocol
protocol Zot {}
protocol Foo {
associatedType Bar: Zot
var prop1: Bar { get set }
}
Now I could say
class Zoty: Zot {}
class Fooy: Foo {
typealias Bar = Zoty
var prop1: Zoty = Zoty()
}
But I haven't quite moved to the class layer yet. Is there a way for me to set the type alias in a protocol like so?
protocol Fooie: Foo {
typealias Bar = Zoty
var prop1: Zoty { get set }
}
The compiler says to make it like this
protocol Fooie: Foo where Bar == Zoty {
var prop1: Bar { get set }
}
But then it throws the error Cannot override mutable property 'prop1' of type 'Self.Bar' with covariant type 'Zoty'
To fix the error, just remove this line in Fooie
var prop1: Bar { get set }
You do not need to redeclare this again, and I do agree the error message is a bit confusing. Swift thinks that you are trying to override the property, which as far as it is concerned, is declared to be a different type, but in this context, the two types can only be the same.
After removing the property, you can now do:
class Fooy: Fooie {
var prop1 = Zoty()
}
and this gives errors
class SomethingElse: Zot {}
class Fooy: Fooie {
var prop1 = SomethingElse()
}
'Fooie' requires the types 'SomethingElse' and 'Zoty' be equivalent
Type 'Fooy' does not conform to protocol 'Fooie'