scala: how to define a value class

Question

Quick question regrading how to define a value class in scala

Here is typical example:

class Wrapper(val underlying: Int) extends AnyVal

I am getting next error:

/usr/home/User/scala2/scala_lerning/src3/val.scala:1: error: value class may not be a member of another class
class Wrapper(val underlying: Int) extends AnyVal
      ^
one error found

Could anyone help with this?

Thanks

The error message seems pretty explicit, a value class cannot be an inner class. — Marth
Sorry, still open question for me. I am compiling this from command promt like: scala value.scala . Should I apply any class modifier in example above? — Pavel
Seems to be related to how the scala command loads files. Compiling with scalac works fine, same with simply typing the line in the REPL or using :load within it. — Marth

Reactormonk Reactormonk · Accepted Answer · 2016-02-18T10:31:38

It seems you're doing

class Foo {
  class Wrapper(val underlying: Int) extends AnyVal
}

which you can't. You have to do

class Foo {
}
class Wrapper(val underlying: Int) extends AnyVal

scala: how to define a value class

1 Answers