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Attribute.Equals Method

This API supports the .NET Framework infrastructure and is not intended to be used directly from your code.

Returns a value that indicates whether this instance is equal to a specified object.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)
'Declaration
Public Overrides Function Equals ( _
	obj As Object _
) As Boolean

Parameters

obj
Type: System.Object
An Object to compare with this instance or Nothing.

Return Value

Type: System.Boolean
true if obj equals the type and value of this instance; otherwise, false.

The following code example defines two custom parameter Attribute classes, then creates several objects of each class and shows the use of the Equals method to compare them.


' Example for the Attribute.Equals( Object ) method.
Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

Namespace NDP_UE_VB

    ' Define a custom parameter attribute that takes a single message argument.
    <AttributeUsage(AttributeTargets.Parameter)>  _
    Public Class ArgumentUsageAttribute
        Inherits Attribute

        ' This is the attribute constructor.
        Public Sub New(UsageMsg As String)
            Me.usageMsg = UsageMsg
        End Sub ' New

        ' usageMsg is storage for the attribute message.
        Protected usageMsg As String

        ' Override ToString() to append the message to what the base generates.
        Public Overrides Function ToString() As String
            Return MyBase.ToString() + ":" + usageMsg
        End Function ' ToString
    End Class ' ArgumentUsageAttribute

    ' Define a custom parameter attribute that generates a GUID for each instance.
    <AttributeUsage(AttributeTargets.Parameter)>  _
    Public Class ArgumentIDAttribute
        Inherits Attribute

        ' This is the attribute constructor, which generates the GUID.
        Public Sub New()
            Me.GUIDinstance = Guid.NewGuid()
        End Sub ' New

        ' instanceGUID is storage for the generated GUID.
        Protected GUIDinstance As Guid

        ' Override ToString() to append the GUID to what the base generates.
        Public Overrides Function ToString() As String
            Return MyBase.ToString() + "." + GUIDinstance.ToString()
        End Function ' ToString
    End Class ' ArgumentIDAttribute

    Public Class TestClass

        ' Assign an ArgumentID attribute to each parameter.
        ' Assign an ArgumentUsage attribute to each parameter.
        Public Sub TestMethod( _
            <ArgumentID(), ArgumentUsage("Must pass an array here.")> _
            strArray() As String, _
            <ArgumentID(), ArgumentUsage("Can pass param list or array here.")> _
            ParamArray strList() As String)
        End Sub ' TestMethod
    End Class ' TestClass

    Module AttributeEqualsDemo

        ' Create Attribute objects and compare them.
        Sub CompareAttributes()

            ' Get the class type, and then get the MethodInfo object 
            ' for TestMethod to access its metadata.
            Dim clsType As Type = GetType(TestClass)
            Dim mInfo As MethodInfo = clsType.GetMethod("TestMethod")

            ' There will be two elements in pInfoArray, one for each parameter.
            Dim pInfoArray As ParameterInfo() = mInfo.GetParameters()
            If Not (pInfoArray Is Nothing) Then

                ' Create an instance of the argument usage attribute on strArray.
                Dim arrayUsageAttr1 As ArgumentUsageAttribute = _
                    Attribute.GetCustomAttribute(pInfoArray(0), _
                        GetType(ArgumentUsageAttribute))

                ' Create another instance of the argument usage attribute 
                ' on strArray.
                Dim arrayUsageAttr2 As ArgumentUsageAttribute = _
                    Attribute.GetCustomAttribute(pInfoArray(0), _
                        GetType(ArgumentUsageAttribute))

                ' Create an instance of the argument usage attribute on strList.
                Dim listUsageAttr As ArgumentUsageAttribute = _
                    Attribute.GetCustomAttribute(pInfoArray(1), _
                        GetType(ArgumentUsageAttribute))

                ' Create an instance of the argument ID attribute on strArray.
                Dim arrayIDAttr1 As ArgumentIDAttribute = _
                    Attribute.GetCustomAttribute(pInfoArray(0), _
                        GetType(ArgumentIDAttribute))

                ' Create another instance of the argument ID attribute on strArray.
                Dim arrayIDAttr2 As ArgumentIDAttribute = _
                    Attribute.GetCustomAttribute(pInfoArray(0), _
                        GetType(ArgumentIDAttribute))

                ' Create an instance of the argument ID attribute on strList.
                Dim listIDAttr As ArgumentIDAttribute = _
                    Attribute.GetCustomAttribute(pInfoArray(1), _
                        GetType(ArgumentIDAttribute))

                ' Compare various pairs of attributes for equality.
                Console.WriteLine(vbCrLf & "Compare a usage attribute instance " & _
                    "to another instance of the same attribute:")
                Console.WriteLine("   ""{0}"" = " & vbCrLf & "   ""{1}"" ? {2}", _
                    arrayUsageAttr1.ToString(), arrayUsageAttr2.ToString(), _
                    arrayUsageAttr1.Equals(arrayUsageAttr2))

                Console.WriteLine(vbCrLf & _
                    "Compare a usage attribute to another usage attribute:")
                Console.WriteLine("   ""{0}"" = " & vbCrLf & "   ""{1}"" ? {2}", _
                    arrayUsageAttr1.ToString(), listUsageAttr.ToString(), _
                    arrayUsageAttr1.Equals(listUsageAttr))

                Console.WriteLine(vbCrLf & "Compare an ID attribute instance " & _
                    "to another instance of the same attribute:")
                Console.WriteLine("   ""{0}"" = " & vbCrLf & "   ""{1}"" ? {2}", _
                    arrayIDAttr1.ToString(), arrayIDAttr2.ToString(), _
                    arrayIDAttr1.Equals(arrayIDAttr2))

                Console.WriteLine(vbCrLf & _
                    "Compare an ID attribute to another ID attribute:")
                Console.WriteLine("   ""{0}"" = " & vbCrLf & "   ""{1}"" ? {2}", _
                    arrayIDAttr1.ToString(), listIDAttr.ToString(), _
                    arrayIDAttr1.Equals(listIDAttr))
            Else
                Console.WriteLine("The parameters information could " & _
                    "not be retrieved for method {0}.", mInfo.Name)
            End If
        End Sub ' CompareAttributes

        Sub Main()
            Console.WriteLine("This example of Attribute.Equals( Object ) " & _
                "generates the following output." )

            CompareAttributes( )

        End Sub ' Main
    End Module ' AttributeEqualsDemo
End Namespace ' NDP_UE_VB

' This example of Attribute.Equals( Object ) generates the following output.
' 
' Compare a usage attribute instance to another instance of the same attribute:
'    "NDP_UE_VB.ArgumentUsageAttribute:Must pass an array here." =
'    "NDP_UE_VB.ArgumentUsageAttribute:Must pass an array here." ? True
' 
' Compare a usage attribute to another usage attribute:
'    "NDP_UE_VB.ArgumentUsageAttribute:Must pass an array here." =
'    "NDP_UE_VB.ArgumentUsageAttribute:Can pass param list or array here." ? False
' 
' Compare an ID attribute instance to another instance of the same attribute:
'    "NDP_UE_VB.ArgumentIDAttribute.aa2c2346-ca87-40d6-afb7-5e3bc1637351" =
'    "NDP_UE_VB.ArgumentIDAttribute.4192c26c-9a7b-4a74-97fc-6c3dfbc2cdfe" ? False
' 
' Compare an ID attribute to another ID attribute:
'    "NDP_UE_VB.ArgumentIDAttribute.aa2c2346-ca87-40d6-afb7-5e3bc1637351" =
'    "NDP_UE_VB.ArgumentIDAttribute.237a7337-15f1-469b-a5ce-7503def917b2" ? False


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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