问题描述
我有一个基础抽象类(特质).它有一个抽象方法foo()
.它由几个派生类扩展和实现.我想创建一个可以混合到派生类中的特征,以便它实现 foo()
然后调用派生类的 foo()
.
I have a base abstract class (trait). It has an abstract method foo()
. It is extended and implemented by several derived classes. I want to create a trait that can be mixed into the derived classes so that it implements foo()
and then calls the derived class's foo()
.
类似于:
trait Foo {
def foo()
}
trait M extends Foo {
override def foo() {
println("M")
super.foo()
}
}
class FooImpl1 extends Foo {
override def foo() {
println("Impl")
}
}
class FooImpl2 extends FooImpl1 with M
我尝试了自我类型和结构类型,但我无法让它工作.
I tried self types and structural types, but I can't get it to work.
推荐答案
你们非常接近.将抽象修饰符添加到 M.foo,您将拥有可堆叠特征"模式:http://www.artima.com/scalazine/articles/stackable_trait_pattern.html
You were very close. Add the abstract modifier to M.foo, and you have the 'Stackable Trait' pattern: http://www.artima.com/scalazine/articles/stackable_trait_pattern.html
trait Foo {
def foo()
}
trait M extends Foo {
abstract override def foo() {println("M"); super.foo()}
}
class FooImpl1 extends Foo {
override def foo() {println("Impl")}
}
class FooImpl2 extends FooImpl1 with M
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