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MemberInfo.IsDefined Method

When overridden in a derived class, indicates whether one or more instance of attributeType is defined on this member.

[Visual Basic]
Public MustOverride Function IsDefined( _
   ByVal attributeType As Type, _
   ByVal inherit As Boolean _
) As Boolean Implements ICustomAttributeProvider.IsDefined
[C#]
public abstract bool IsDefined(
 Type attributeType,
 bool inherit
);
[C++]
public: virtual bool IsDefined(
 Type* attributeType,
 bool inherit
) = 0;
[JScript]
public abstract function IsDefined(
   attributeType : Type,
 inherit : Boolean
) : Boolean;

Parameters

attributeType
The Type object to which the custom attributes are applied.
inherit
Specifies whether to search this member's inheritance chain to find the attributes.

Return Value

true if one or more instance of attributeType is defined on this member; otherwise false.

Implements

ICustomAttributeProvider.IsDefined

Example

[Visual Basic, C#, C++] The following example determines whether the specified attribute is defined on the specified member.

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

' 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 MemberInfo_GetCustomAttributes_IsDefined

    Public Shared Sub Main()
        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)
                    Console.WriteLine(ControlChars.Cr + "The attributes of type MyAttribute for the member {0} are: " + ControlChars.Cr, myMembers(i))
                    Dim j As Integer
                    For j = 0 To myAttributes.Length - 1
                        ' Display the value associated with the attribute.
                        Console.WriteLine("The value of the attribute is : ""{0}""", CType(myAttributes(j), MyAttribute).Name)
                    Next j
                End If
            Next i
        Catch e As Exception
            Console.WriteLine("An exception occurred: {0}", e.Message)
        End Try
    End Sub 'Main
End Class 'MemberInfo_GetCustomAttributes_IsDefined

[C#] 

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 MemberInfo_GetCustomAttributes_IsDefined
{
    public static void Main()
    {
        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);
                    Console.WriteLine("\nThe attributes of type MyAttribute for the member {0} are: \n",
                        myMembers[i]);
                    for(int j = 0; j < myAttributes.Length; j++)
                        // Display the value associated with the attribute.
                        Console.WriteLine("The value of the attribute is : \"{0}\"",
                            ((MyAttribute)myAttributes[j]).Name);
                }
            }
        }
        catch(Exception e)
        {
            Console.WriteLine("An exception occurred: {0}", e.Message);
        }
    }
}

[C++] 

#using <mscorlib.dll>

using namespace System;
using namespace System::Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets::All)]
public __gc class MyAttribute : public Attribute
{
private:
   String* myName;
public:
   MyAttribute(String* name)
   {
      myName = name;
   }
   __property String* get_Name()
   {
      return myName;
   }
};

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

int main()
{
   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);
            Console::WriteLine(S"\nThe attributes of type MyAttribute for the member {0} are: \n",
               myMembers->Item[i]);
            for (int j = 0; j < myAttributes->Length; j++)
               // Display the value associated with the attribute.
               Console::WriteLine(S"The value of the attribute is : \"{0}\"",
               (__try_cast<MyAttribute*>(myAttributes[j]))->Name);
         }
      }
   } catch (Exception* e) {
      Console::WriteLine(S"An exception occurred: {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

See Also

MemberInfo Class | MemberInfo Members | System.Reflection Namespace

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