F#一个扩展方法引用另一个

Question

[<Extension>]
static member ToOrganizationRequest<'T when 'T :> OrganizationRequest> (entity: Entity) =
    let request = Activator.CreateInstance(typeof<'T>) :?> OrganizationRequest
    request.Parameters.Item "Target" <- entity
    request

[<Extension>]
static member ToOrganizationRequest<'T when 'T :> OrganizationRequest> (entities: seq<Entity>) = 
    entities
    |> Seq.map (fun x -> x.ToOrganizationRequest<'T>())

第二种扩展方法无法引用第一种方法,因此

|> Seq.map(有趣的x - > x.ToOrganizationRequest <'T>())

失败,因为我无法使用ToOrganizationRequest.有没有办法让它理解参考？

Answer 1

如果你不需要在C#中看到你的扩展方法,你可以(也可能应该)扩展这样的Entity类型:

type Entity with
    member this.ToOrganizationRequest<'T when 'T :> OrganizationRequest>() =
        let request = Activator.CreateInstance(typeof<'T>) :?> OrganizationRequest
        request.Parameters.Item "Target" <- entity
        request

这将允许您的第二个C#样式扩展方法按照您最初编写它的方式运行:

[<Extension>]
type Ext =
    [<Extension>]
    static member ToOrganizationRequest<'T when 'T :> OrganizationRequest> (entities: seq<Entity>) = 
        entities
        |> Seq.map (fun x -> x.ToOrganizationRequest<'T>())

如果你确实需要在C#中使用它们,则必须在扩展方法定义的类型内静态调用另一个扩展方法.

[<Extension>]
type Ext =
    [<Extension>]
    static member ToOrganizationRequest<'T when 'T :> OrganizationRequest> (entity: Entity) =
        let request = Activator.CreateInstance(typeof<'T>) :?> OrganizationRequest
        request.Parameters.Item "Target" <- entity
        request

    [<Extension>]
    static member ToOrganizationRequest<'T when 'T :> OrganizationRequest> (entities: seq<Entity>) = 
        entities  
        |> Seq.map (Ext.ToOrganizationRequest)

您可以在此处阅读有关F#文档中各种类型的扩展方法的更多信息.