3 people like it.

Easy use of IDisposable

A fun little trick.

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open System
open System.IO
open System.Threading

let print (message : obj) = Console.WriteLine message

let usable (work : Lazy<unit>) : IDisposable =
    { new IDisposable with
        member this.Dispose () : unit =
            work.Value
    }

let main () =
    use __ = usable (lazy print "Disposing!")
    print "begin work"
    Thread.Sleep 1500
    //failwith "boom!"
    print "end work"

main ()
namespace System
namespace System.IO
namespace System.Threading
val print : message:obj -> unit

Full name: Script.print
val message : obj
type obj = Object

Full name: Microsoft.FSharp.Core.obj
type Console =
  static member BackgroundColor : ConsoleColor with get, set
  static member Beep : unit -> unit + 1 overload
  static member BufferHeight : int with get, set
  static member BufferWidth : int with get, set
  static member CapsLock : bool
  static member Clear : unit -> unit
  static member CursorLeft : int with get, set
  static member CursorSize : int with get, set
  static member CursorTop : int with get, set
  static member CursorVisible : bool with get, set
  ...

Full name: System.Console
Console.WriteLine() : unit
   (+0 other overloads)
Console.WriteLine(value: string) : unit
   (+0 other overloads)
Console.WriteLine(value: obj) : unit
   (+0 other overloads)
Console.WriteLine(value: uint64) : unit
   (+0 other overloads)
Console.WriteLine(value: int64) : unit
   (+0 other overloads)
Console.WriteLine(value: uint32) : unit
   (+0 other overloads)
Console.WriteLine(value: int) : unit
   (+0 other overloads)
Console.WriteLine(value: float32) : unit
   (+0 other overloads)
Console.WriteLine(value: float) : unit
   (+0 other overloads)
Console.WriteLine(value: decimal) : unit
   (+0 other overloads)
val usable : work:Lazy<unit> -> IDisposable

Full name: Script.usable
val work : Lazy<unit>
Multiple items
active recognizer Lazy: Lazy<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.( |Lazy| )

--------------------
type Lazy<'T> =
  new : unit -> Lazy<'T> + 5 overloads
  member IsValueCreated : bool
  member ToString : unit -> string
  member Value : 'T

Full name: System.Lazy<_>

--------------------
Lazy() : unit
Lazy(valueFactory: Func<'T>) : unit
Lazy(isThreadSafe: bool) : unit
Lazy(mode: LazyThreadSafetyMode) : unit
Lazy(valueFactory: Func<'T>, isThreadSafe: bool) : unit
Lazy(valueFactory: Func<'T>, mode: LazyThreadSafetyMode) : unit
type unit = Unit

Full name: Microsoft.FSharp.Core.unit
type IDisposable =
  member Dispose : unit -> unit

Full name: System.IDisposable
val this : IDisposable
IDisposable.Dispose() : unit
property Lazy.Value: unit
val main : unit -> unit

Full name: Script.main
Multiple items
type Thread =
  inherit CriticalFinalizerObject
  new : start:ThreadStart -> Thread + 3 overloads
  member Abort : unit -> unit + 1 overload
  member ApartmentState : ApartmentState with get, set
  member CurrentCulture : CultureInfo with get, set
  member CurrentUICulture : CultureInfo with get, set
  member DisableComObjectEagerCleanup : unit -> unit
  member ExecutionContext : ExecutionContext
  member GetApartmentState : unit -> ApartmentState
  member GetCompressedStack : unit -> CompressedStack
  member GetHashCode : unit -> int
  ...

Full name: System.Threading.Thread

--------------------
Thread(start: ThreadStart) : unit
Thread(start: ParameterizedThreadStart) : unit
Thread(start: ThreadStart, maxStackSize: int) : unit
Thread(start: ParameterizedThreadStart, maxStackSize: int) : unit
Thread.Sleep(timeout: TimeSpan) : unit
Thread.Sleep(millisecondsTimeout: int) : unit
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More information

Link:http://fssnip.net/nl
Posted:5 years ago
Author:BR
Tags: idisposable , use , using , raii , trick