java是否可以将Kotlin的bydelegation用于现有的类/对象（即Arrow的）？

Question

我有几个专门的类，我想用Kotlin和Arrow创建，它们将围绕一个Arrow或monad。我创建了下面的代码来使用Kotlin的委托，但我想知道它是否可以简化或变得更地道。如有任何建议，将不胜感激

感谢您的时间和兴趣

internal data class EitherWrapper<L,R>(private var delegate: Either<L,R>) {
     internal operator fun getValue(thisRef: Any?, property: KProperty<*>): Either<L,R> {
        return delegate
    }

    internal operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Either<L,R>) {
        delegate = value
    }
}

fun main(args: Array<String>) {
    val delegate: Either<Exception, String> = Right("howdy")
    val myeither: Either<Exception, String> by EitherWrapper(delegate)
    println("IsLeft(): ${myeither.isLeft()}")
    println("IsRight(): ${myeither.isRight()}")
}

Answer 1

所以，我想我有一个解决问题的办法。下面的代码将一个“任意”封装在一个新类型中：Exception。这段代码是我想要构建的起点。最终，我会有如下内容：

我可以通过后端服务传递这种类型的实例，并返回更精确的异常、错误或值

interface EitherMonad<L, R> {
    val either: Either<L, R>
}

class BaseEitherMonad<L, R>(
    override val either: Either<L, R>
) : EitherMonad<L, R>

class Exceptional<R>(
    private val delegate: EitherMonad<Exception, R>
) : EitherMonad<Exception, R> by delegate {}

fun main() {

    val delegateRight = BaseEitherMonad<Exception, String>(Either.Right("howdy"))
    val exceptionalRight = Exceptional(delegateRight)
    println("IsLeft(): ${exceptionalRight.either.isLeft()}")
    println("IsRight(): ${exceptionalRight.either.isRight()}")
    exceptionalRight.either.fold({ throw it }, { println("Right: $it") })
    exceptionalRight.either.map { println(it) }

    val delegateLeft = BaseEitherMonad<Exception, String>(Either.Left(IllegalStateException("Boom!")))
    val exceptionalLeft = Exceptional(delegateLeft)
    println("IsLeft(): ${exceptionalLeft.either.isLeft()}")
    println("IsRight(): ${exceptionalLeft.either.isRight()}")
    exceptionalLeft.either.fold({ throw it }, { println("Right: $it") })
    exceptionalLeft.either.map { println(it) }
}

跑步：

Answer 2

您的代码是正确的，据我所知，您唯一能做的改进是使其通用，而不是具体，如下所示：

internal data class DelegateWrapper<T>(private var delegate: T) {
  internal operator fun getValue(thisRef: Any?, property: KProperty<*>): T = 
    delegate

  internal operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
    delegate = value
  }
}