Use a static Java declaration in macro implementation

Question

I am trying to use a static method on a Java class, T, in a macro implementation:

def macroImpl[T : c.WeakTypeTag](c: Context): c.Expr[ResultType] = {
  import c.universe._
  val tpe = weakTypeOf[T]
  val someStaticMethod = tpe.declaration(c.universe.newTermName("someStaticMethod")).asMethod
  c.Expr[ResultType] { q""" new ResultType {
    def myMethod = ${someStaticMethod.name.toTermName}  
  }"""}
}

This does not work. When I print out all the members and declarations of tpe, the static methods that I want to use are not there. How do I access these static methods and use them in the quasiquote?

I am using version 2.1.0 of the macro-paradise compiler plugin for scala 2.10.6.

Static methods are modeled as methods on the companion object. — som-snytt, Dec 28 '15 at 05:46
@som-snytt How do I get to the companion? It looks like in the 2.11 API I can do `tpe.companion` but I am using 2.10 — mushroom, Dec 28 '15 at 07:45

mushroom · Accepted Answer · 2016-01-03T20:59:22.027

After seeing @som-snytt's comment, I investigated how to access the companion object. The code ended up looking something like this:

def macroImpl[T : c.WeakTypeTag](c: Context): c.Expr[ResultType] = {
  import c.universe._
  val tpe = weakTypeOf[T]
  val companion = tpe.typeSymbol.companionSymbol
  c.Expr[ResultType] { q""" new ResultType {
    def myMethod = ${companion.name.toTermName}.someStaticMethod  
  }"""}
}

I look up the companion symbol and then call the method someStaticMethod on it in the quasiquote. This seems to do what I want.

I can get the declarations of companion by doing companion.typeSignature.declarations

Use a static Java declaration in macro implementation

1 Answers1