我想(静态)反射(reflect)这样的示例类:
case class Foo[T,U](stuff:T, more:U, age:Int) {
val ignore:Boolean = false
}
我开始是这样的:
val symbol = currentMirror.classSymbol(clazz) // symbol is universe.ClassSymbol
// I want to know about type placeholders T and U
val typeParamArgs = symbol.typeParams.map( tp => tp.name.toString)
if( symbol.isCaseClass ) {
val tsig = symbol.typeSignature
println(tsig)
}
好的,在这一点上,如果我打印tsig,我会看到:
[T, U]scala.AnyRef
with scala.Product
with scala.Serializable {
val stuff: T
private[this] val stuff: T
val more: U
private[this] val more: U
val age: scala.Int
private[this] val age: scala.Int
def <init>(stuff: T,more: U,age: scala.Int): co.blocke.Foo[T,U]
val ignore: scala.Boolean
private[this] val ignore: scala.Boolean
def copy[T, U](stuff: T,more: U,age: scala.Int): co.blocke.Foo[T,U]
def copy$default$1[T, U]: T @scala.annotation.unchecked.uncheckedVariance
def copy$default$2[T, U]: U @scala.annotation.unchecked.uncheckedVariance
def copy$default$3[T, U]: scala.Int @scala.annotation.unchecked.uncheckedVariance
override def productPrefix: java.lang.String
def productArity: scala.Int
def productElement(x$1: scala.Int): scala.Any
override def productIterator: Iterator[scala.Any]
def canEqual(x$1: scala.Any): scala.Boolean
override def hashCode(): scala.Int
override def toString(): java.lang.String
override def equals(x$1: scala.Any): scala.Boolean
}
用看到中间的那一行吗?那就是我要反省的宣言。满足了我的需求。
如何分离tsig(universe.Type)以获取有关的信息? (我不需要有关“忽略”的信息。)
最佳答案
不用检查类的.typeSignature
,而是使用.primaryConstructor.typeSignature
检查构造函数的类型签名:
val csig = symbol.primaryConstructor.typeSignature
val params = csig.paramLists.head // paramLists returns a List of Lists
这为您提供了主要构造函数的参数列表,因此您可以查询名称,类型等:
scala> params(1).name
res47: reflect.runtime.universe.Symbol#NameType = more
scala> params(2).typeSignature
res48: reflect.runtime.universe.Type = scala.Int