IsDefined Method

MemberInfo.IsDefined Method

Updated: January 2010

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)

'Declaration
Public MustOverride Function IsDefined ( _
	attributeType As Type, _
	inherit As Boolean _
) As Boolean
'Usage
Dim instance As MemberInfo 
Dim attributeType As Type 
Dim inherit As Boolean 
Dim returnValue As Boolean 

returnValue = instance.IsDefined(attributeType, _
	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)
_MemberInfo.IsDefined(Type, Boolean)

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.

NoteNote:

In the .NET Framework version 2.0, this method returns true if a type, method, or constructor has security attributes stored in the new metadata format. Assemblies compiled with version 2.0 use this format. Dynamic assemblies and assemblies compiled with earlier versions of the .NET Framework use the old XML format. See Emitting Declarative Security Attributes.

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

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

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

Date

History

Reason

January 2010

Clarified that the inherit parameter is ignored for properties and events.

Customer feedback.

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