Implements trait with an anonymous object in Scala

Question

I have a trait definition:

trait T {
  def name: String
}

I can create an object like:

val o = new {
  val name: String = "anonymous"
} with T

But I cannot create the object in the following way:

val o = new {
  def name: String = "anonymous"
} with T

The compiler said ';' or newline expected in line } with T. The only different is I used def instead of val in the second implementation.

I know that method can be defined in an anonymous object, but why I cannot use in this way here?

The compiler error I get is "error: only concrete field definitions allowed in early object initialization section" — john sullivan, Nov 06 '15 at 04:59

score 3 · Accepted Answer · edited May 23 '17 at 11:53

3

The curly brackets in your two examples are "early definitions", explained here:

So it's initialization code, and not something that gets mixed in to your object.

The idea was raised on the Scala JIRA, and closed as "not a bug", here:

edited May 23 '17 at 11:53

Community

answered Nov 06 '15 at 04:57

john sullivan

1 Answers1