CODEWITHSUNDEEP
scalaconstants
Rich Oliver
Rich Oliver

Reputation: 6109

Scala:Constant properties val or def

I've got an integer Coordinate Structure for a Hex grid, that I'm porting from C# to Scala as follows:

object Cood
{
  def Up = new Cood(0, 2)
  def UpRight = new Cood(1, 1)
  def DownRight = new Cood(1,- 1)
  def Down = new Cood(0, - 2)
  def DownLeft = new Cood(- 1, - 1)
  def UpLeft = new Cood(- 1, + 1)
  def None = new Cood(0, 0)
}

class Cood(val x: Int, val y: Int)
{
   //more code
}

As there were no constants for non basic types they were static get properties. In Scala should I implement them as def s or val s or does it not matter?

Upvotes: 1

Views: 374

Answers (2)

Luigi Plinge
Luigi Plinge

Reputation: 51109

You should probably implement your Cood class as a case class:

case class Cood(x: Int, y: Int)

That's it, no need for additional getters / setters, equality method, toString, or extractor for pattern matching.

If you just want it as a normal class, however, just write class Cood(val x: Int, val y: Int).

Upvotes: 2

dhg
dhg

Reputation: 52681

You should implement them as val. The def keyword defines a method, so every time it is called, the method will be executed. In other words, with val the Cood object will be created once and stored, but with def a new copy will be created every time you go to access it.

If you are worried about creating object that may not be used, then you should try lazy val, which is a val that is only populated the first time it is accessed.

Upvotes: 5

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