DefaultMemberAttribute Class

Defines the member of a type that is the default member used by InvokeMember.

Namespace:  System.Reflection
Assembly:  mscorlib (in mscorlib.dll)

[SerializableAttribute]
[ComVisibleAttribute(true)]
[AttributeUsageAttribute(AttributeTargets.Class|AttributeTargets.Struct|AttributeTargets.Interface)]
public sealed class DefaultMemberAttribute : Attribute

A property is imported as an indexer (default indexed property in Visual Basic) if the property has arguments and if the name of the property or one of its accessors matches the name specified by the DefaultMemberAttribute. If the DefaultMemberAttribute is not present on the containing type, then the type does not have an indexer. The C# compiler emits the DefaultMemberAttribute on any type containing an indexer. In C# it is an error to manually attribute a type with the DefaultMemberAttribute if the type also declares an indexer.

The following example uses the DefaultMemberAttribute attribute to make the Age property the default member of the MyClass class.

using System;
using System.Reflection;
using System.IO;

[DefaultMemberAttribute("Age")]   
public class MyClass
{
    public void Name(String s) {}
    public int Age
    {
        get
        {
            return 20;
        }
    }
    public static void Main()
    {
        try
        {
            Type  myType = typeof(MyClass);
            MemberInfo[] memberInfoArray = myType.GetDefaultMembers();
            if (memberInfoArray.Length > 0)
            {
                foreach(MemberInfo memberInfoObj in memberInfoArray)
                {
                    Console.WriteLine("The default member name is: " + memberInfoObj.ToString());
                }
            }
            else
            {
                Console.WriteLine("No default members are available."); 
            }
        }
        catch(InvalidOperationException e)
        {
            Console.WriteLine("InvalidOperationException: " + e.Message);
        }
        catch(IOException e)
        {
            Console.WriteLine("IOException: " + e.Message);
        }
        catch(Exception e)
        {
            Console.WriteLine("Exception: " + e.Message);
        }
    }
}

System.Object
  System.Attribute
    System.Reflection.DefaultMemberAttribute

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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