Generics 如何在F中使用类型注释实现泛型#

我有以下代码框架：

type MyException<'T> () =
    inherit Exception()

type IMyInterface =
    abstract member Method<'T when 'T : (new: unit -> 'T) and 'T :> Exception> : string -> int

type MyClass =
    interface IMyInterface with
        member this.Method s =
            let i = s.IndexOf "a"
            if i = -1 then raise (new MyException<'T> ())
            i

键入MyException（））
我

然而，我得到了以下信息：

此构造导致代码不像类型注释所指示的那样通用。类型变量“T”已被约束为类型“obj”

编译时，

obj

被传递给MyException，而不是

'T

---

我需要对

IMyInterface.Method

具有上述类型约束，还需要将传递的类型传递到

MyClass.Method

中的

MyException

。我怎样才能做到这一点呢？

我想你必须参数化

MyClass

：

type MyClass<'T> =
    interface IMyInterface with
        member this.Method s =
            let i = s.IndexOf "a"
            if i = -1 then raise (new MyException<'T> ())
            i

键入MyClass（））
我

或者对方法重复约束：

type MyClass =
    interface IMyInterface with
        member this.Method<'T when 'T : (new: unit -> 'T) and 'T :> Exception> s =
            let i = s.IndexOf "a"
            if i = -1 then raise (new MyException<'T> ())
            i

类型MyClass=
接口imy接口
成员。方法'T）和'T:>Exception>s=
设i=s.IndexOf“a”
如果i=-1，则raise（新的MyException我认为您必须参数化
MyClass
：

type MyClass<'T> =
    interface IMyInterface with
        member this.Method s =
            let i = s.IndexOf "a"
            if i = -1 then raise (new MyException<'T> ())
            i

键入MyClass（））
我

或者对方法重复约束：

type MyClass =
    interface IMyInterface with
        member this.Method<'T when 'T : (new: unit -> 'T) and 'T :> Exception> s =
            let i = s.IndexOf "a"
            if i = -1 then raise (new MyException<'T> ())
            i

类型MyClass=
接口imy接口
成员。方法'T）和'T:>Exception>s=
设i=s.IndexOf“a”
如果i=-1，则引发（新的MyException