Question

我需要检查任何对象的类型并获取相应的对象。但是，不能通过将T传递给正常的功能参数来解析T。您需要进行比较，直到所有类型参数都匹配为止。

trait Wrap[T]

trait Interface
trait InterfaceA extends Interface
trait InterfaceB extends Interface

object InterfaceAImpl extends Wrap[InterfaceA] with Candidate
object InterfaceBImpl extends Wrap[InterfaceB] with Candidate

trait Mediate[T <: Interface] {
  val t: T = get[Wrap[T]]
}

object A extends Mediate[InterfaceA]
object B extends Mediate[InterfaceB]

def get[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[Option[T]] = {
    import c.universe._

    // Find an object that mixes in a specific interface
    // Suppose that the result is [[object A]] and [[object B]]
    val detected: List[Symbol] = new CandidateExtractor[c.type](c).run[Candidate]

    // This result is
    // "InterfaceAImpl =:= Wrap[T]"
    // "InterfaceBImpl =:= Wrap[T]"
    // When called from A, it expects Wrap[InterfaceA] instead of Wrap[T]
    detected.foreach(x => println(s"${x.typeSignature} =:= ${weakTypeOf[T]}"))

    // Find objects that inherits Wrap [T] among objects that inherit a specific interface
    val r = detected.collectFirst {
      // Wrap[InterfaceA] and Wrap[T] are compared, so all false.
      case x if x.typeSignature =:= weakTypeOf[T] => x
    }

    c.Expr[Option[T]](
      q"$r"
    )
  }

有没有办法比较继承关系，包括泛型？

第二次尝试

因此，我要做的是...

object A的{{1}} = t: T，因为它继承了InterfaceAImpl
Wrap[InterfaceA]的{{1}} = object B，因为它继承了t: T

因此InterfaceBImpl无效。
必须为Wrap[InterfaceB]
和<:<(typeOf[Wrap[_])

Answer 1

尝试

List(typeOf[Wrap[_]].typeSymbol, typeOf[Candidate].typeSymbol).forall(x.typeSignature.baseClasses.contains)

或

List(typeOf[Wrap[_]].typeSymbol, typeOf[Candidate].typeSymbol).forall(x.typeSignature.baseType(_) match { case _ : TypeRef => true; case NoType => false })

如何比较抽象的WeakTypeTag的未表示泛型

第二次尝试

1 个答案: