CODEWITHSUNDEEP
scalascala-reflectscala-implicits
Bert Becker
Bert Becker

Reputation: 41

Scala: get outer class from inner class in constructor

I have an anonymous inner class, and I want to acces the (anonymous) outer class of it in the constructor. So I want to implement this method:

new Outer {
  new Inner {

  }
}

class Outer {

}

class Inner {
  def outerClass: Outer = ???
}

Upvotes: 0

Views: 174

Answers (2)

Alexey Romanov
Alexey Romanov

Reputation: 170723

You can do this using implicits easily enough (I assume both Outer and Inner can be modified, but the code using them should look like in the question). Declarations:

class Outer {
  implicit def o: Outer = this
}

class Inner(implicit val outerClass: Outer) {
}

Usage:

new Outer {
  new Inner {
    // can use outerClass here
  }
}

or

new Outer {
  val inner = new Inner {

  }

  // inner.outerClass
}

And I can imagine this being useful for DSLs, but be sure you(r API's users) actually want it first!

Upvotes: 1

sascha10000
sascha10000

Reputation: 1230

What speaks against this approach?

new Outer { self =>
  new Inner(self) {

  }
}

class Outer {
}

class Inner[A](outerClass:A) {
  println("CLASS: " + outerClass.getClass)
}

Upvotes: 2

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