F#使用自定义类进行设置 [英] F# Set using custom class

问题描述

我正在尝试将Set操作与我拥有的类一起使用.此类的每个实例都有一个唯一的ID.我是否需要实现System.IComparable接口，如果需要，该怎么办?

I'm trying to use Set operations with a class that I have. Every instance of this class has a unique ID. Do I need to implement the System.IComparable interface and if so how would I?

type SomeClass(id : int) =
    member this.ID = id

let someSet = Set.of_list [SomeClass(1); SomeClass(2)]
let test = someSet.Contains(SomeClass(2))    

推荐答案

以下是应该有效的实现:

Here's an implementation that should work:

type SomeClass(id : int) =    
    member this.ID = id
    override this.Equals(o) =
        match o with
        | :? SomeClass as sc -> this.ID = sc.ID
        | _ -> false
    override this.GetHashCode() =
        id.GetHashCode()
    interface System.IComparable with
        member this.CompareTo(o) =
            match o with
            | :? SomeClass as sc -> compare this.ID sc.ID
            | _ -> -1

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