CODEWITHSUNDEEP
scalaoperatorsdsl
ayvango
ayvango

Reputation: 5977

How make operator call this inside a class

I'm writing a small DSL. It may be used as a custom control structure from other point of view.

Here comes little example

case class Reference(var value : Double) {
  def apply() = value
  def update(v : Double) = value = v
}
implicit def toReference(ref:Reference) = ref.value

trait Store {
  import scala.collection.mutable.Buffer
  val index : Buffer[Reference] = Buffer()
  def ++ (v : Double) : Reference = {
    val r = Reference(v)
    index += r
    r
  }
  implicit def toSelf(u : Unit) = this
}

class ExampleStore extends Store {
  val a = () ++ 1.0
  val b = () ++ 2.0
  val c = () ++ 0.5
}


val store = new ExampleStore
store.c() = store.a + store.b

I'd like to access class operators with no preceding this but could not find other way than specifying at least () at start of expressions. A "prefix" form is what I need

Some way to rewrite this example as following

class ExampleStore extends Store {
  val a =++ 1.0
  val b =++ 2.0
  val c =++ 0.5
}

Could anyone think of some trick to make scala accept such convention?

Upvotes: 1

Views: 87

Answers (1)

paradigmatic
paradigmatic

Reputation: 40461

Writing ++ 1.0 means that ++ is an unary operator of 1.0 (class Double). However, in Scala unary operators are limited to ! ~ - +. So theres is no way to implement the syntax you whish.

But you can still use parenthesis:

class ExampleStore extends Store {
  val a = ++(1.0)
  val b = ++(2.0)
  val c = ++(3.0)
}

Upvotes: 1

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