我写这产生一些像这样的代码宏:
q"_root_.ru.lmars.macropack.TagsAndTags2.$tagName(..$tagParams)"
但我想生成只有$tagName
定义这个代码,并有一定的“标记”(如注释或一些特殊的返回类型)。如何获得Symbol
对这个$tagName
?
这很容易,如果$tagName
是TagsAndTags2
对象中定义的:
object TagsAndTags2
{
def dialog(caption: String): String = ???
}
你可以写这样的事情来获得Symbol
dialog
的:
val tagParentAccess = q"_root_.ru.lmars.macropack.TagsAndTags2"
val tagParent = c.typecheck(tagParentAccess, silent = true)
val tagSymbol = tagParent.tpe.member(tagName)
但如何做同样的,如果通过$tagName
的隐式转换可用?
implicit final class UserTags(x: TagsAndTags2.type)
{
def dialog(caption: String): String = ???
}
这里是一个快速和肮脏的例子(我已经试过了在斯卡拉2.11):
温度/ Foo.scala:
package temp
import scala.language.experimental.macros
object Foo {
def printSymbol(name: String): Unit = macro FooMacro.printSymbol
}
object FooTarget
private class FooMacro(val c: scala.reflect.macros.blackbox.Context) {
import c.universe._
def printSymbol(name: Tree): Tree = {
name match {
case Literal(Constant(lv)) =>
val a = q"_root_.temp.FooTarget.${TermName(lv.toString)}"
val ca = c.typecheck(a)
println("checked apply symbol", ca.symbol)
}
q"()"
}
}
温度/ Bar.scala:
package temp
object Implicits {
implicit class BarObjContainer(f: FooTarget.type) {
object bar
}
}
object UseMacro {
import Implicits._
val v = Foo.printSymbol("bar")
}
是ca.symbol
你想要什么?
=== UPDATE ===
这里是快速和肮脏的演示与PARAM功能:
温度/ Foo.scala:
package temp
import scala.language.experimental.macros
object Foo {
def printSymbol(name: String): Unit = macro FooMacro.printSymbol
}
object FooTarget
private class FooMacro(val c: scala.reflect.macros.blackbox.Context) {
import c.universe._
def printSymbol(name: Tree): Tree = {
name match {
case Literal(Constant(lv)) =>
val nameStr = lv.toString
val f = q"_root_.temp.FooTarget.${TermName(nameStr)}(_)"
c.typecheck(f) match {
case Function(_, Apply(s@Select(_, TermName(`nameStr`)), _)) =>
println(s.symbol)
}
}
q"()"
}
}
温度/ Bar.scala:
package temp
object Implicits {
implicit class BarObjContainer(f: FooTarget.type) {
def bar(baz: String): Unit = ()
}
}
object UseMacro {
import Implicits._
val v = Foo.printSymbol("bar")
}
s
为“杆”的方法的符号。