scala如何处理一个类扩展一个类的泛型本身？ [英] How does scala handle a class extends a class with a generic of itself?

问题描述

  class Person extend Friend [Person] 
  

如果类A扩展了B [B] A] ，类 A 作为类型构造函数参数显示。这个重现没有什么特别之处，也就是说，它与类A扩展B [C] 没有区别。

例如，如果 B 是trait 已订购：

  class Person（val name：String，val age：Int）extends Ordered [Person] {
 // in method`compare（that：A）`of Ordered， `替换为`Person` 
 def compare（that：Person）：Int = {
 val i = this.name compare..name 
 if（i！= 0）i else this .age compare the.age 
} 
} 
  

class Person extends Friend[Person] 

How does Person been explained while it extends a Friend[Person] class ?

解决方案

If class A extends B[A], class A appears as a type constructor parameter of itself. There is nothing special about this reappearance, i.e. it's no different from a class A extends B[C].

For example, if B was trait Ordered:

class Person(val name: String, val age: Int) extends Ordered[Person] {
  // in method `compare(that: A)` of Ordered, type `A` is replaced with `Person`
  def compare(that: Person): Int = {
    val i = this.name compare that.name
    if (i != 0) i else this.age compare that.age
  }
}

这篇关于scala如何处理一个类扩展一个类的泛型本身？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！