CODEWITHSUNDEEP
kotlin
Ray Zhang
Ray Zhang

Reputation: 1561

Kotlin: cannot access enum defined in companion object

According to Kotlin documentation:

Members of the companion object can be called by using simply the class name as the qualifier.

Why does it not seem to work here?

class Foo {
  companion object {
    enum class Type { A, B, C }
  }
}

class Bar {
  val typeA = Foo.Companion.Type.A  // works
  val typeB = Foo.Type.B            // error: "Unresolved reference: Type"
}

Upvotes: 6

Views: 3159

Answers (1)

hotkey
hotkey

Reputation: 148189

Comparing the two qualified type names, Foo.Type.A and Foo.Companion.Type.A , the former would rather mean a type declared directly inside the Foo's scope.

The latter form, therefore, is used to disambiguate types declared inside a type from ones declared inside its nested types and object declarations (including the companion object).

class Foo {
    class Bar // Foo.Bar

    companion object {
        class Bar // Foo.Companion.Bar
    }
    object Baz {
        class Bar // Foo.Baz.Bar
    }
}

As Pawel noted, nested types and object declarations are not members and have different resolution rules than those of functions and properties.

Upvotes: 5

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