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CustomAttributeBuilder Class

Helps build custom attributes.

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

<ComVisibleAttribute(True)> _
<ClassInterfaceAttribute(ClassInterfaceType.None)> _
<HostProtectionAttribute(SecurityAction.LinkDemand, MayLeakOnAbort := True)> _
Public Class CustomAttributeBuilder _
	Implements _CustomAttributeBuilder
Dim instance As CustomAttributeBuilder


The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: MayLeakOnAbort. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

Use the CustomAttributeBuilder object returned by the constructor to describe the custom attribute. Associate the CustomAttribute with a builder instance by calling the SetCustomAttribute method on that builder instance. For example, create a CustomAttributeBuilder to describe an instance of AssemblyCultureAttribute by supplying the constructor of AssemblyCultureAttribute and its argument. Then call SetCustomAttribute on an AssemblyBuilder to establish the association.

The following code sample illustrates the use of CustomAttributeBuilder.

Imports System
Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit


' We will apply this custom attribute to our dynamic type. 
Public Class ClassCreator

   Inherits Attribute

   Private creator As String 

   Public ReadOnly Property GetCreator() As String 
         Return creator
      End Get 
   End Property 

   Public Sub New(name As String)
      Me.creator = name
   End Sub 'New 

End Class 'ClassCreator

' We will apply this dynamic attribute to our dynamic method. 
Public Class DateLastUpdated

   Inherits Attribute

   Private dateUpdated As String 

   Public ReadOnly Property GetDateUpdated() As String 
         Return dateUpdated
      End Get 
   End Property 

   Public Sub New(theDate As String)
      Me.dateUpdated = theDate
   End Sub 'New 

End Class 'DateLastUpdated

Class MethodBuilderCustomAttributesDemo

   Public Shared Function BuildTypeWithCustomAttributesOnMethod() As Type

      Dim currentDomain As AppDomain = Thread.GetDomain()

      Dim myAsmName As New AssemblyName()
      myAsmName.Name = "MyAssembly" 

      Dim myAsmBuilder As AssemblyBuilder = currentDomain.DefineDynamicAssembly(myAsmName, _

      Dim myModBuilder As ModuleBuilder = myAsmBuilder.DefineDynamicModule("MyModule")

      ' First, we'll build a type with a custom attribute attached. 
      Dim myTypeBuilder As TypeBuilder = myModBuilder.DefineType("MyType", _

      Dim ctorParams() As Type = {GetType(String)}
      Dim classCtorInfo As ConstructorInfo = GetType(ClassCreator).GetConstructor(ctorParams)

      Dim myCABuilder As New CustomAttributeBuilder(classCtorInfo, _
						New Object() {"Joe Programmer"})


      ' Now, let's build a method and add a custom attribute to it. 
      Dim myMethodBuilder As MethodBuilder = myTypeBuilder.DefineMethod("HelloWorld", _
					MethodAttributes.Public, Nothing, New Type() {})

      ctorParams = New Type() {GetType(String)}
      classCtorInfo = GetType(DateLastUpdated).GetConstructor(ctorParams)

      Dim myCABuilder2 As New CustomAttributeBuilder(classCtorInfo, _
						New Object() {DateTime.Now.ToString()})


      Dim myIL As ILGenerator = myMethodBuilder.GetILGenerator()

      myIL.EmitWriteLine("Hello, world!")

      Return myTypeBuilder.CreateType()

   End Function 'BuildTypeWithCustomAttributesOnMethod

   Public Shared Sub Main()

      Dim myType As Type = BuildTypeWithCustomAttributesOnMethod()

      Dim myInstance As Object = Activator.CreateInstance(myType)

      Dim customAttrs As Object() = myType.GetCustomAttributes(True)

      Console.WriteLine("Custom Attributes for Type 'MyType':")

      Dim attrVal As Object = Nothing 

      Dim customAttr As Object
      For Each customAttr In  customAttrs
         attrVal = GetType(ClassCreator).InvokeMember("GetCreator", _
						BindingFlags.GetProperty, _
						Nothing, customAttr, New Object() {})
         Console.WriteLine("-- Attribute: [{0} = ""{1}""]", customAttr, attrVal)
      Next customAttr

      Console.WriteLine("Custom Attributes for Method 'HelloWorld()' in 'MyType':")

      customAttrs = myType.GetMember("HelloWorld")(0).GetCustomAttributes(True)

      For Each customAttr In  customAttrs
         attrVal = GetType(DateLastUpdated).InvokeMember("GetDateUpdated", _
						BindingFlags.GetProperty, _
						Nothing, customAttr, New Object() {})
         Console.WriteLine("-- Attribute: [{0} = ""{1}""]", customAttr, attrVal)
      Next customAttr


      Console.WriteLine(myType.InvokeMember("HelloWorld", BindingFlags.InvokeMethod, _
						Nothing, myInstance, New Object() {}))
   End Sub 'Main

End Class 'MethodBuilderCustomAttributesDemo


Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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

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