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.Reflection

' 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(ByVal 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.")> ByVal _
       strArray() As String, _
       <ArgumentID(), ArgumentUsage("Can pass param list or array here.")> ByVal _
       ParamArray strList() As String)
   End Sub ' TestMethod
End Class ' TestClass

Module Example

   ' Create Attribute objects and compare them.
   Sub CompareAttributes(ByVal outputBlock As System.Windows.Controls.TextBlock)

      ' 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.
         outputBlock.Text &= vbCrLf & "Compare a usage attribute instance " & _
             "to another instance of the same attribute:" & vbCrLf
         outputBlock.Text &= String.Format("   ""{0}"" = " & vbCrLf & "   ""{1}"" ? {2}", _
             arrayUsageAttr1.ToString(), arrayUsageAttr2.ToString(), _
             arrayUsageAttr1.Equals(arrayUsageAttr2)) & vbCrLf

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

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

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

   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      outputBlock.Text &= "This example of Attribute.Equals( Object ) " & _
          "generates the following output." & vbCrLf

      CompareAttributes(outputBlock)

   End Sub 
End Module 
' 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


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

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

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