Article
11/18/2011

MemberInfo.IsDefined Method

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When overridden in a derived class, indicates whether one or more attributes of the specified type or of its derived types is applied to this member.

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

Syntax

'Declaration
Public MustOverride Function IsDefined ( _
    attributeType As Type, _
    inherit As Boolean _
) As Boolean

public abstract bool IsDefined(
    Type attributeType,
    bool inherit
)

Parameters

attributeType
Type: System.Type
The type of custom attribute to search for. The search includes derived types.

inherit
Type: System.Boolean
true to search this member's inheritance chain to find the attributes; otherwise, false. This parameter is ignored for properties and events; see Remarks.

Return Value

Type: System.Boolean
true if one or more instances of attributeType or any of its derived types is applied to this member; otherwise, false.

Implements

ICustomAttributeProvider.IsDefined(Type, Boolean)

Remarks

This method ignores the inherit parameter for properties and events. To search the inheritance chain for attributes on properties and events, use the appropriate overloads of the Attribute.IsDefined method.

Examples

The following example determines whether the specified attribute is applied to the specified member.

Note:
To run this example, see Building Examples That Use a Demo Method and a TextBlock Control.

Imports System.Reflection

' Define a custom attribute with one named parameter.
<AttributeUsage(AttributeTargets.All)> Public Class MyAttribute
   Inherits Attribute
   Private myName As String

   Public Sub New(ByVal name As String)
      myName = name
   End Sub 'New

   Public ReadOnly Property Name() As String
      Get
         Return myName
      End Get
   End Property
End Class 'MyAttribute

' Define a class that has the custom attribute associated with one of its members.
Public Class MyClass1

   <MyAttribute("This is an example attribute.")> Public Sub MyMethod(ByVal i As Integer)
      Return
   End Sub 'MyMethod
End Class 'MyClass1

Public Class Example

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Try
         ' Get the type of MyClass1.
         Dim myType As Type = GetType(MyClass1)
         ' Get the members associated with MyClass1.
         Dim myMembers As MemberInfo() = myType.GetMembers()

         ' Display the attributes for each of the members of MyClass1.
         Dim i As Integer
         For i = 0 To myMembers.Length - 1
            ' Display the attribute if it is of type MyAttribute.
            If myMembers(i).IsDefined(GetType(MyAttribute), False) Then
               Dim myAttributes As [Object]() = myMembers(i).GetCustomAttributes(GetType(MyAttribute), False)
               outputBlock.Text += String.Format(ControlChars.Cr + "The attributes of type MyAttribute for the member {0} are: " + ControlChars.Cr, myMembers(i)) & vbCrLf
               Dim j As Integer
               For j = 0 To myAttributes.Length - 1
                  ' Display the value associated with the attribute.
                  outputBlock.Text += String.Format("The value of the attribute is : ""{0}""", CType(myAttributes(j), MyAttribute).Name) & vbCrLf
               Next j
            End If
         Next i
      Catch e As Exception
         outputBlock.Text += String.Format("An exception occurred: {0}", e.Message) & vbCrLf
      End Try
   End Sub 'Main
End Class 'MemberInfo_GetCustomAttributes_IsDefined


using System;
using System.Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets.All)]
public class MyAttribute : Attribute
{
   private string myName;
   public MyAttribute(string name)
   {
      myName = name;
   }
   public string Name
   {
      get
      {
         return myName;
      }
   }
}

// Define a class that has the custom attribute associated with one of its members.
public class MyClass1
{
   [MyAttribute("This is an example attribute.")]
   public void MyMethod(int i)
   {
      return;
   }
}

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      try
      {
         // Get the type of MyClass1.
         Type myType = typeof(MyClass1);
         // Get the members associated with MyClass1.
         MemberInfo[] myMembers = myType.GetMembers();

         // Display the attributes for each of the members of MyClass1.
         for (int i = 0; i < myMembers.Length; i++)
         {
            // Display the attribute if it is of type MyAttribute.
            if (myMembers[i].IsDefined(typeof(MyAttribute), false))
            {
               Object[] myAttributes = myMembers[i].GetCustomAttributes(typeof(MyAttribute), false);
               outputBlock.Text += String.Format("\nThe attributes of type MyAttribute for the member {0} are: \n",
                   myMembers[i]) + "\n";
               for (int j = 0; j < myAttributes.Length; j++)
                  // Display the value associated with the attribute.
                  outputBlock.Text += String.Format("The value of the attribute is : \"{0}\"",
                      ((MyAttribute)myAttributes[j]).Name) + "\n";
            }
         }
      }
      catch (Exception e)
      {
         outputBlock.Text += String.Format("An exception occurred: {0}", e.Message) + "\n";
      }
   }
}

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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