How to call a method within a constructor?

Monday, April 01, 2013 6:24 PM

Hi,

I have a question about classes in F# and hope you can help.

I'm trying call a static method from a constructor like this:

type Node(one : Node option, two : Node option) =
  member this.Value = GetValue one + GetValue two
  static member GetValue (some : Node option) =
    match some with
    | Some(s) -> s.Value
    | None -> 0

The desired result looks like this in C#:

class Node {
  readonly Int32 Value;
  static Int32 GetValue(Node some) {
    return some == null ? 0 : some.Value;
  }
  public Node(Node one, Node two) {
    Value = GetValue(one) + GetValue(two);
  }
}

Could you suggest a way to resolve this?

Edited by Borys Dibrov Monday, April 01, 2013 6:24 PM

All Replies

Monday, April 01, 2013 7:50 PM

Moderator

1
In F# you need to qualify static method names with the type name (even if you're defining another member within the same type):
```
  member this.Value = Node.GetValue one + Node.GetValue two
```
- Proposed As Answer by Keith BattocchiMicrosoft Contingent Staff, Moderator Monday, April 01, 2013 7:50 PM
- Marked As Answer by Borys Dibrov Monday, April 01, 2013 8:04 PM
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Monday, April 01, 2013 7:51 PM

Use type qualifier: Node.GetValue

type Node(one : Node option, two : Node option) =
  member this.Value = Node.GetValue one + Node.GetValue two
  static member GetValue (some : Node option) =
    match some with
    | Some(s) -> s.Value
    | None -> 0

Petr

Marked As Answer by Borys Dibrov Monday, April 01, 2013 8:04 PM

Tuesday, April 02, 2013 4:19 AM

You can use private "let" functions instead:

type Node(?one: Node, ?two: Node) =
    let getValue (node: Node option) = 
        match node with 
        | Some n -> n.Value
        | _ -> 0
    member this.Value = getValue one + getValue two