A recent interview of Martin Odersky on SE-Radio introduces this and other nice features that are in the works for Scala: http://www.se-radio.net/2011/02/episode-171-scala-update-wit...

Last week I spent a little bit of time trying to figure out how the Dynamic trait works and what its good for.

I managed to do a quick and dirty 5 minute mockup of a "Callable" Map that lets you invoke keys as method names:

https://gist.github.com/797513

examples with XML tree

https://gist.github.com/783394

what to call it?

http://groups.google.com/group/scala-language/browse_thread/...

  def invokeDynamic(name: String)(args: Any*) = {
    println("Invoke Dynamic: (name = %s)(args: %s)".format(name, args))
    get(name.asInstanceOf[String])
  }

Why do you need the asInstanceOf(), when name is already declared to be a String?

Sorry if this is obvious; I don't know Scala (I've glanced at it, but the 2.8 compiler is too slow on my laptop--as in, about one line per minute).

Sorry, you don't. It's a leftover from an earlier attempt to do something different with dynamic.

Your assumption is correct: It is already a string and there is no purpose to casting it to a String.

I don't recall exactly where that artifact came from but I recall the original release of Dynamic had a very different method signature and I was fiddling to figure out the new signatures when I wrote this. The examples I found when I wrote this used the old interface and the new one had no docs or examples yet so I did a bit of playing.

I've updated the gist to remove the unnecessary asInstanceOf and demonstrate it as proper code.

Ah, nice. Thanks for answering.

"You're going the wrong way!"

http://www.youtube.com/watch?v=NEZv0FUPtcc

I guess scala isn't already complex or rather implicit enough.

Is this implemented as a library or does it also require changes to the language/compiler?

It required a small language change, which I believe you can see in it's entirety here: https://lampsvn.epfl.ch/trac/scala/changeset/23993