Question

Is it possible to initialize a class parameter with a function in Scala?

Example:

def square(x: Int) = x*x

class Foo(val x: Int = square(x))

This doesn’t compile but I hope you get the idea.

Answer 1

Hard to guess what you’re trying to achieve, but let me have a go:

class Foo private (val x: Int)

object Foo {
  def apply(x: Int) = new Foo(square(x))
}

Note that if you try this in the REPL, you must enter both the class and its companion object at the same time (in paste mode, via :pa), or the object Foo won’t have access to the private class constructor.

This applies the square function to the parameter x before creating a Foo instance:

scala> Foo(3).x
res1: Int = 9