Looking at some scala-docs of my libraries, it appeared to me that there is some unwanted noise from value classes. For example:
implicit class RichInt(val i: Int) extends AnyVal {
def squared = i * i
}
This introduces an unwanted symbol i
:
4.i // arghh....
That stuff appears both in the scala docs and in the IDE auto completion which is really not good.
So... any ideas of how to mitigate this problem? I mean you can use RichInt(val self: Int)
but that doesn't make it any better (4.self
, wth?)
EDIT:
In the following example, does the compiler erase the intermediate object, or not?
import language.implicitConversions
object Definition {
trait IntOps extends Any { def squared: Int }
implicit private class IntOpsImpl(val i: Int) extends AnyVal with IntOps {
def squared = i * i
}
implicit def IntOps(i: Int): IntOps = new IntOpsImpl(i) // optimised or not?
}
object Application {
import Definition._
// 4.i -- forbidden
4.squared
}
Value classes are a new mechanism which help to avoid allocating run time objects. AnyVal define value classes. Value classes are predefined, they coincide to the primitive kind of Java-like languages. There are nine predefined value types : Double, Float, Long, Int, Short, Byte, Char, Unit, and Boolean.
Class methods are methods that are called on a class rather than an instance. They are typically used as part of an object meta-model. I.e, for each class, defined an instance of the class object in the meta-model is created. Meta-model protocols allow classes to be created and deleted.
The rule is that a method should be made provided unless it is needed. One of the main reasons for this is that in a future release of an API etc., you can always make a private function public, but you can almost never make a previous public function private without breaking existing code.
To call a class method, put the class as the first argument. Class methods can be can be called from instances and from the class itself. All of these use the same method. The method can use the classes variables and methods.
In Scala 2.11 you can make the val private, which fixes this issue:
implicit class RichInt(private val i: Int) extends AnyVal {
def squared = i * i
}
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