访问在类内部委托接口方法的实例答案

【问题标题】：Access the instance by which methods of an interface are delegated inside of the class访问在类内部委托接口方法的实例
【发布时间】：2022-08-15 02:57:18
【问题描述】：

有没有办法访问在类内部委托接口的方法的实例？

class Class1(): Interface2 by Class2() { // NOTE: Class2() is here a concrete implementation by which the methods of Interface2 are delegated.
  // I want to access the instance by which the Interface2 is delegated (Class2()) in here.
}

现在我这样做：

private val class2Instance = Class2()
class Class1(): Interface2 by class2Instance { // NOTE: Class2() is here a concrete implementation by which the methods of Interface2 are delegated.
  val class2: Class2 by ::class2Instance // the value class2 now grants me access to class2Instance
}

但我不认为这是一个好方法，因为类必须访问在任何类之外声明的值。

标签： kotlin delegation

【解决方案1】：

您可以将Class2 设为Class1 的属性和构造函数参数，然后通过该参数进行委托：

class Class1(val class2: Class2): Interface2 by class2

这样你就不需要从Class1 内部对Class1 外部定义的class2Interface 的引用，但你必须将它作为构造函数参数传递：

val class1 = Class1(class2Instance)

【讨论】：