Question

Is it possible to create static member indexed properties in F#? MSDN show them only for instance members, however, I’m able to define the following class:

type ObjWithStaticProperty =
    static member StaticProperty
        with get () = 3
        and  set (value:int) = ()

    static member StaticPropertyIndexed1
        with get (x:int) = 3
        and  set (x:int) (value:int) = ()

    static member StaticPropertyIndexed2
        with get (x:int,y:int) = 3
        and  set (x:int,y:int) (value:int) = ()

//Type signature given by FSI:
type ObjWithStaticProperty =
  class
    static member StaticProperty : int
    static member StaticPropertyIndexed1 : x:int -> int with get
    static member StaticPropertyIndexed2 : x:int * y:int -> int with get
    static member StaticProperty : int with set
    static member StaticPropertyIndexed1 : x:int -> int with set
    static member StaticPropertyIndexed2 : x:int * y:int -> int with set
  end

But when I try to use one, I get an error:

> ObjWithStaticProperty.StaticPropertyIndexed2.[1,2] <- 3;;

  ObjWithStaticProperty.StaticPropertyIndexed2.[1,2] <- 3;;
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error FS1187: An indexer property must be given at least one argument

I tried a few different syntax variations and none worked. Also weird is that when I hover over set in VS2010 for one of the definitions in the type, I get info about ExtraTopLevelOperators.set.

Answer 1

I believe that you call indexed properties using a different syntax (whether instance or static):

ObjWithStaticProperty.StaticPropertyIndexed2(1,2) <- 3

The only semi-exception to this is that an Item property on an instance x can be called via x.[...] (that is, Item is omitted and brackets are used around the arguments).