IsValueClass

A base trait for a user-defined value-class that standardizes the name of the value-class val to "underlying" and toString to underlying toString. This allows creating a conversion from an instance of any value-class to its underlying representation.

For details on value-class see: http://docs.scala-lang.org/overviews/core/value-classes.html

Example value-class: implicit class Name(underlying: String) extends AnyVal with IsValueType[String]

Note1: When using creating a value-class for String, it is necessary to create an implicit view to StringOps to use the Scala extended String methods on instances of the value-class. Example for Name above: object Name { import scala.collection.immutable.StringOps implicit def stringOps_Name(n: Name) = new StringOps(n.underlying) }

Note2: while almost every method on underlying can be used on the value-class without special code, the equals method is a special case that still requires wrapping the right-hand type in the value-class to match the other side. Ex:

Name("Hal") == "Hal" // always returns false + compiler warning Name("Hal") == Name("Hal") // works correctly