DefaultMemberAttribute Class

May 11, 2014

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

System.Object
  System.Attribute
    System.Reflection.DefaultMemberAttribute

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

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

The DefaultMemberAttribute type exposes the following members.

  NameDescription
Public methodDefaultMemberAttributeInitializes a new instance of the DefaultMemberAttribute class.
Top

  NameDescription
Public propertyMemberNameGets the name from the attribute.
Top

  NameDescription
Public methodEqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Top

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 Example
{
   public void Name(String s) { }
   public int Age
   {
      get
      {
         return 20;
      }
   }
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      try
      {
         Type myType = typeof(Example);
         MemberInfo[] memberInfoArray = myType.GetDefaultMembers();
         if (memberInfoArray.Length > 0)
         {
            foreach (MemberInfo memberInfoObj in memberInfoArray)
            {
               outputBlock.Text += "The default member name is: " + memberInfoObj.ToString() + "\n";
            }
         }
         else
         {
            outputBlock.Text += "No default members are available." + "\n";
         }
      }
      catch (InvalidOperationException e)
      {
         outputBlock.Text += "InvalidOperationException: " + e.Message + "\n";
      }
      catch (IOException e)
      {
         outputBlock.Text += "IOException: " + e.Message + "\n";
      }
      catch (Exception e)
      {
         outputBlock.Text += "Exception: " + e.Message + "\n";
      }
   }
}


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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

Show:
© 2014 Microsoft