constructor - 无法编译内部构造函数调用原因 :Primary constructor call expected

Question

假设我们有以下主要和次要构造函数:

open class Animal(val name:String){
  internal constructor(message:InputStream): this(readName(message))
}

为什么不能调用父类(super class)的内部构造函数？

class Dog(name:String):Animal(name){
   internal constructor(message:InputStream):super(message)
                                             ^^^^^
                                             Primary constructor call expected
}

编辑

显然，当主构造函数转换为辅助构造函数或完全删除时，它会编译。

class Dog:Animal{
   constructor(name:String):super(name)
   internal constructor(message:InputStream):super(message)

}

这是编译器错误吗？

Answer 1

来自 docs :

If the class has a primary constructor, each secondary constructor needs to delegate to the primary constructor, either directly or indirectly through another secondary constructor(s). Delegation to another constructor of the same class is done using the this keyword

和:

If the class has no primary constructor, then each secondary constructor has to initialize the base type using the super keyword, or to delegate to another constructor which does that.

您的 Dog类有一个主构造函数，所以你必须使用 this 委托(delegate)给它.
如果去掉主构造函数，可以引用 super构造函数:

class Dog : Animal {
    constructor(message: InputStream) : super(message)
}

(以上没有错误)