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Core.DefaultValueAttribute Class (F#)

Adding this attribute to a field declaration means that the field is not initialized. During type checking a constraint is asserted that the field type supports null. If the Check value is false then the constraint is not asserted.

Namespace/Module Path: Microsoft.FSharp.Core

Assembly: FSharp.Core (in FSharp.Core.dll)

[<AttributeUsage(AttributeTargets.Field, AllowMultiple = false)>]
[<Sealed>]
type DefaultValueAttribute =
 class
  new DefaultValueAttribute : bool -> DefaultValueAttribute
  new DefaultValueAttribute : unit -> DefaultValueAttribute
  member this.Check :  bool
 end

This attribute is intended to be used on explicit fields in classes and structures. It shouldn't be used on records. For more information, see Records (F#) and Explicit Fields: The val Keyword (F#).

The .NET Framework namespace System.ComponentModel defines an attribute that has the same name: DefaultValueAttribute. Therefore, you must fully qualify the F# attribute if you open the System.ComponentModel namespace.

You can also use the short form of the name, DefaultValue.

Member

Description

new

Creates an instance of the attribute

Member

Description

Check

Indicates if a constraint is asserted that the field type supports 'null'

Windows 8, Windows 7, Windows Server 2012, Windows Server 2008 R2

F# Core Library Versions

Supported in: 2.0, 4.0, Portable

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