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Type.GetDefaultMembers Method

Searches for the members defined for the current Type whose DefaultMemberAttribute is set.

[Visual Basic]
Public Overridable Function GetDefaultMembers() As MemberInfo()
[C#]
public virtual MemberInfo[] GetDefaultMembers();
[C++]
public: virtual MemberInfo* GetDefaultMembers() [];
[JScript]
public function GetDefaultMembers() : MemberInfo[];

Return Value

An array of MemberInfo objects representing all default members of the current Type.

-or-

An empty array of type MemberInfo, if the current Type does not have default members.

Remarks

This method can be overridden by a derived class.

Members include properties, methods, fields, events, and so on.

The following table shows what members of a base class are returned by the Get methods when reflecting on a type.

Member Type Static Non-Static
Constructor No No
Field No Yes. A field is always hide-by-name-and-signature.
Event Not applicable The common type system rule is that the inheritance is the same as that of the methods that implement the property. Reflection treats properties as hide-by-name-and-signature. See note 2 below.
Method No Yes. A method (both virtual and non-virtual) can be hide-by-name or hide-by-name-and-signature.
Nested Type No No
Property Not applicable The common type system rule is that the inheritance is the same as that of the methods that implement the property. Reflection treats properties as hide-by-name-and-signature. See note 2 below.
  1. Hide-by-name-and-signature considers all of the parts of the signature, including custom modifiers, return types, parameter types, sentinels, and unmanaged calling conventions. This is a binary comparison.
  2. For reflection, properties and events are hide-by-name-and-signature. If you have a property with both a get and a set accessor in the base class, but the derived class has only a get accessor, the derived class property hides the base class property, and you will not be able to access the setter on the base class.
  3. Custom attributes are not part of the common type system.

Example

[Visual Basic, C#, C++] The following example obtains the default member information of MyClass and displays the default members.

[Visual Basic] 
Imports System
Imports System.Reflection
Imports System.IO
Imports Microsoft.VisualBasic

<DefaultMemberAttribute("Age")> Public Class [MyClass]

    Public Sub Name(ByVal s As String)
    End Sub 'Name

    Public ReadOnly Property Age() As Integer
        Get
            Return 20
        End Get
    End Property

    Public Shared Sub Main()
        Try
            Dim myType As Type = GetType([MyClass])
            Dim memberInfoArray As MemberInfo() = myType.GetDefaultMembers()
            If memberInfoArray.Length > 0 Then
                Dim memberInfoObj As MemberInfo
                For Each memberInfoObj In memberInfoArray
                    Console.WriteLine("The default member name is: " + memberInfoObj.ToString())
                Next memberInfoObj
            Else
                Console.WriteLine("No default members are available.")
            End If
        Catch e As InvalidOperationException
            Console.WriteLine("InvalidOperationException: " + e.Message)
        Catch e As IOException
            Console.WriteLine("IOException: " + e.Message)
        Catch e As Exception
            Console.WriteLine("Exception: " + e.Message)
        End Try
    End Sub 'Main
End Class '[MyClass]

[C#] 

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);
        }
    }
}

[C++] 

#using <mscorlib.dll>

using namespace System;
using namespace System::Reflection;
using namespace System::IO;

[DefaultMemberAttribute(S"Age")]
public __gc class MyClass {
public:
   void Name(String* s) {}

   __property int get_Age() {
      return 20;
   }
};

int main() {
   try {
      Type*  myType = __typeof(MyClass);
      MemberInfo*  memberInfoArray[] = myType->GetDefaultMembers();
      if (memberInfoArray->Length > 0) {
         System::Collections::IEnumerator* myEnum = memberInfoArray->GetEnumerator();
         while (myEnum->MoveNext()) {
            MemberInfo* memberInfoObj = __try_cast<MemberInfo*>(myEnum->Current);

            Console::WriteLine(S"The default member name is: {0}", memberInfoObj);
         }
      } else {
         Console::WriteLine(S"No default members are available.");
      }
   } catch (InvalidOperationException* e) {
      Console::WriteLine(S"InvalidOperationException: {0}", e->Message);
   } catch (IOException* e) {
      Console::WriteLine(S"IOException: {0}", e->Message);
   } catch (Exception* e) {
      Console::WriteLine(S"Exception: {0}", e->Message);
   }
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework, Common Language Infrastructure (CLI) Standard

See Also

Type Class | Type Members | System Namespace | MemberInfo | DefaultMemberAttribute | GetMember | GetMembers | FindMembers

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