抽象类和特征之间的区别 [英] Difference between Abstract Class and Trait

问题描述

可能的重复:
Scala 特征与抽象类

抽象类和特征之间的概念区别是什么?

What is the conceptual difference between abstract classes and traits?

推荐答案

一个类只能扩展一个超类，因此只有一个抽象类.如果你想组合几个类，Scala 的方法是使用 mixin class composition:你组合一个(可选)超类、您自己的成员定义和一个或多个特征.与类相比，trait 受到限制，因为它不能有构造函数参数(比较 scala 参考手册).

A class can only extend one superclass, and thus, only one abstract class. If you want to compose several classes the Scala way is to use mixin class composition: you combine an (optional) superclass, your own member definitions and one or more traits. A trait is restricted in comparison to classes in that it cannot have constructor parameters (compare the scala reference manual).

引入了与类相比的特性限制，以避免多重继承的典型问题.关于继承层次，有或多或少复杂的规则；最好避免在这实际上很重要的层次结构.;-) 据我所知，只有从两个不同的特征继承两个具有相同签名的方法/两个具有相同名称的变量才重要.

The restrictions of traits in comparison to classes are introduced to avoid typical problems with multiple inheritance. There are more or less complicated rules with respect to the inheritance hierarchy; it might be best to avoid a hierarchy where this actually matters. ;-) As far as I understand, it can only matter if you inherit two methods with the same signature / two variables with the same name from two different traits.

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