Scala通用方法覆盖 [英] scala generic method overriding

问题描述

我有一个抽象类:

abstract class Foo(...){
   def bar1(f : Foo) : Boolean
   def bar2(f : Foo) : Foo
}

多个类扩展了Foo并覆盖了方法

multiple classes extend Foo and override the methods

class FooImpl(...) extends Foo{
    override def bar1(f : Foo) : Boolean {
        ...
    }
    override def bar2(f : Foo) : Foo {
        ...
    }
} 

是否可以使用泛型(或其他方法)使重写方法具有实现它的子类的参数类型?像这样:

Is it possible, using generics (or something) to make the overriding methods have the parametertype of the subclass implementing it? Like this :

class FooImpl(...) extends Foo{
    override def bar1(f : FooImpl) : Boolean {
        ...
    }
    override def bar2(f : FooImpl) : FooImpl {
        ...
    }
}

我在考虑以下内容，但这似乎没有效果...

I was thinking something along the line of the following, but that didn't seem to work...

abstract class Foo(...){
    def bar1[T <: Foo](f : T) : Boolean
    def bar2[T <: Foo](f : T) : T
}

class FooImpl(...) extends Foo{
    override def bar1[FooImpl](f : FooImpl) : Boolean {
       ...
    }
    override def bar2[FooImpl](f : FooImpl) : FooImpl{
       ...
    }
}

非常感谢您的帮助！

谢谢.

推荐答案

abstract class Foo{
   type T <: Foo
   def bar1(f:T):Boolean
   def bar2(f:T):T
}

class FooImpl extends Foo{
   type T = FooImpl
   override def bar1(f:FooImpl) = true
   override def bar2(f:FooImpl) = f
}

在此版本中，Foo的不同子类都将Foo共享为超类，但在设置中将bar2的返回值(或bar1或bar2的参数)保留为您了解对象(假设它名为obj)是它是Foo，您需要使用类型obj.T作为变量的类型.

In this version, different subclasses of Foo all share Foo as a superclass, but to hold the return value of bar2 (or the parameters to bar1 or bar2) in a setting where all you know about your object (let's say it's named obj) is that it's a Foo, you need to use the type obj.T as the type of the variable.

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