f# - F#连铸基地

当我想将base上载到适当的接口类型(即A)以便可以对其调用doA()时，出现解析错误。我知道base(http://cs.hubfs.net/topic/None/58670)有点特殊，但到目前为止，我仍无法找到解决此特定问题的方法。

有什么建议？

type A =
    abstract member doA : unit -> string

type ConcreteA() =
    interface A with
        member this.doA() = "a"

type ExtA() =
    inherit ConcreteA()


interface A with
    override this.doA() = "ex" // + (base :> A).doA() -> parse error (unexpected symbol ':>' in expression)

((new ExtA()) :> A).doA() // output: ex

等效的工作C#:

public interface A
{
    string doA();
}

public class ConcreteA : A {
    public virtual string doA() { return "a"; }
}

public class ExtA : ConcreteA {
    public override string doA() { return "ex" + base.doA(); }
}

new ExtA().doA(); // output: exa

最佳答案

这等效于您的C#:

type A =
    abstract member doA : unit -> string

type ConcreteA() =
    abstract doA : unit -> string
    default this.doA() = "a"
    interface A with
        member this.doA() = this.doA()

type ExtA() =
    inherit ConcreteA()
    override this.doA() = "ex" + base.doA()

ExtA().doA() // output: exa

base不能单独使用，只能用于成员访问(因此存在解析错误)。请参见Classes on MSDN下的“指定继承”。