在Kotlin中，可以在运行时更改委派吗? [英] In Kotlin, is it possible to change delegation at Runtime?

问题描述

为以下代码生成的字节码在Derived类中创建一个private final Base $$delegate_0字段.分配了可变字段b后，原始委托不会更改.

The generated byte code for the below code creates a private final Base $$delegate_0 field in the Derived class. When the mutable field b is assigned the original delegate does not change.

是否有一种在保持zero boilerplate实现的同时在运行时更改委托的方法?

Is there a way to change the delegate at runtime while keeping the zero boilerplate implementation?

interface Base {
    fun print()
}

class BaseImpl(val x: Int) : Base {
    override fun print() { println(x) }
}

class Derived(var b: Base) : Base by b

fun main(args: Array) {
    val b = BaseImpl(10)
    val derived = Derived(b)
    derived.print()// prints 10

    derived.b = BaseImpl(20)
    derived.print()// prints 10
}

该示例摘自docs https://kotlinlang.org/docs/reference/delegation .html 并进行了编辑.

The sample is taken from the docs https://kotlinlang.org/docs/reference/delegation.html and edited.

推荐答案

否，Kotlin从1.1版开始不支持此功能，但是正在考虑将其用于将来的版本.这是由此功能请求跟踪的.

No, this is not supported in Kotlin as of version 1.1, but this is under consideration for a future version. This is tracked by this feature request.

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