The rules for the override keyword on non-required initializers seem overly constraining as they prevent expressing shadowing when parameters match, but other aspects of the declaration differ:
class Base {
init() {}
}
class ThrowingDerived: Base {
// error: overriding declaration requires an 'override' keyword
// error: cannot override non-throwing initializer with throwing initializer
init() throws { super.init() }
}
class FailableDerived: Base {
// error: overriding declaration requires an 'override' keyword
// error: failable initializer 'init()' cannot override a non-failable initializer
init?() { return nil }
}
I think these derived initializers should be considered shadowing, not overriding (which introduces the additional constraints) since the base initializer is not required. The only way I found to achieve the shadowing semantics is to introduce a dummy intermediate base with different parameters:
class Base {
init() {}
}
class Dummy: Base {
// Hides 'init()' so derived classes can redeclare it
init(_: Void = ()) { super.init() }
}
class ThrowingDerived: Dummy {
init() throws { super.init() }
}
class FailableDerived: Dummy {
init?() { return nil }
}
Is this a defect in the language (in which case I'd promote this to a pitch), or is there additional syntax I'm unaware of?