A type for key would be nice. (instead of String)

[Raymond Roestenburg]

Same for version. Int is a bit much for that as well. And you don't want negative values right?

[Age Mooij]

Using a type for keys instead of a String sounds ok but I thought about it a bit a while ago and I couldn't come up with any good reason why you'd want that. Care to suggest one?

Since the only version numbers are generated internally through type-safe Vn classes, the Int doesn't seem like such a huge risk of generating negative versions. What would be the alternative?

[Raymond Roestenburg]

Like a nonemptystring nothing fancy
On Sun 8 Feb 2015 at 18:38 Age Mooij [e-mail] wrote:

Using a type for keys instead of a String sounds ok but I thought about it
a bit a while ago and I couldn't come up with any good reason why you'd
want that. Care to suggest one?

Since the only version numbers are generated internally through type-safe
Vn classes, the Int doesn't seem like such a huge risk of generating
negative versions. What would be the alternative?

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#4 (comment).

[Age Mooij]

I looked around and there doesn't seem to have been anyone online who has created a compile-time checker for non-emptiness in Strings.

The easy answer would be to just check at runtime but where would be the fun in that? NonEmptyString macro coming up I guess... PRs welcome ;)

[Age Mooij]

How about this:

Almost done with the commit and I learned me some macro stuff again ;)

[Age Mooij]

  case class Key(value: String) {
    import java.nio.charset.StandardCharsets.UTF_8
    def getUtf8Bytes: Array[Byte] = value.getBytes(UTF_8)
    override def toString = value
  }

  object KeyMacro {
    import scala.reflect.macros.Context

    def nonEmptyStringToKey(c: Context)(in: c.Tree): c.Tree = {
      import c.universe._
      val q"${ s: String }" = q"${in}"
      if (s.isEmpty) c.abort(c.enclosingPosition, s"Persistence keys must be non-empty!")
      else q"Key($in)"
    }
  }

  implicit def nonEmptyStringToKey(in: String): Key = macro KeyMacro.nonEmptyStringToKey

Notice the unlifting to get back a String to check for emptiness. This will be in stamina soon.

[Age Mooij]

I've been trying to get the Macros to be backwards compatible with 2.10 but that's pretty damn tricky it seems 😢

[Age Mooij]

Closing this for now. There doesn't seem to enough reason or interest for typing persister keys. Perhaps the public beta release will bring back similar requests at a later date.