F＃->访问x。 从让

Question

As the title says, then I want to access x. from a let instead of a member.

The following works:

type UploadController() =
    inherit Controller()

    member x.UploadPath 
        with get() = x.Server.MapPath "~/Uploads" 

But this:

type UploadController() =
    inherit Controller()

    let uploadPath = x.Server.MapPath "~/Uploads" 

Throws a compiler error:

The namespace or module 'x' is not defined

Mission impossible?

Answer 1

You can define a reference like this:

type UploadController () as x =
    inherit Controller ()

    let uploadPath = x.Server.MapPath "~/Uploads" 

Answer 2

ChaosPandion has given the general answer, but it's probable that you don't need a self-identifier in your specific case. Assuming Server is defined in Controller or one of its base classes, you can use base. instead of a self-identifier. This is described in the F# docs :

The keyword base is available in derived classes and refers to the base class instance. It is used like the self-identifier.