Dynamic updateDynamic and macros

[Chris Reeves]

I'm trying to implement updateDynamic as a macro in a trait on scala 2.10.1. There is a matching selectDynamic that works, and, if I change the updateDynamic to a plain println with the given name and value, it works. The macro version, however, gives a "macros cannot be partially applied" error in the repl.

Also, if I change updateDynamic to applyDynamic, the macro version works. Calling updateDynamic manually also works.

Is there a special trick to getting updateDynamic to work as a macro, or have I completely missed something?

Thanks, Chris

[Eugene Burmako]

Could you provide an example?

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[Chris Reeves]

This is the smallest example I could come up with:

trait Bippy extends scala.Dynamic {
  def selectDynamic(name: String) = macro Bippy.select
  def updateDynamic(name: String)(value: Any) = macro Bippy.update
  def applyDynamic(name: String)(value: Any) = macro Bippy.update
}
object Bippy {
  import scala.reflect.macros.Context
  def select(c: Context)(name: c.Expr[String]): c.Expr[String] = name
  def update(c: Context)(name: c.Expr[String])(value: c.Expr[Any]): c.Expr[String] = name
}

I hope gmail doesn't mangle it.

Thanks, Chris

[Eugene Burmako]

Looks like a bug. Could you please submit it?

In the meanwhile, there's a workaround:

import language.dynamics

trait Bippy extends scala.Dynamic {
  def selectDynamic(name: String) = macro Bippy.select

  def updateDynamic(name: String) = Dingus
}
object Dingus {
  def apply(value: Any) = macro Bippy.update

}
object Bippy {
  import scala.reflect.macros.Context
  def select(c: Context)(name: c.Expr[String]): c.Expr[String] = name

  def update(c: Context)(value: c.Expr[Any]): c.Expr[String] = ??? // c.prefix will contain the name
}

[Chris Reeves]

That works nicely. Thanks!

https://issues.scala-lang.org/browse/SI-7428

Thanks, Chris