CustomAttributeBuilder Class

CustomAttributeBuilder Class

 

Helps build custom attributes.

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

System.Object
  System.Reflection.Emit.CustomAttributeBuilder

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

NameDescription
System_CAPS_pubmethodCustomAttributeBuilder(ConstructorInfo, Object())

Initializes an instance of the CustomAttributeBuilder class given the constructor for the custom attribute and the arguments to the constructor.

System_CAPS_pubmethodCustomAttributeBuilder(ConstructorInfo, Object(), FieldInfo(), Object())

Initializes an instance of the CustomAttributeBuilder class given the constructor for the custom attribute, the arguments to the constructor, and a set of named field/value pairs.

System_CAPS_pubmethodCustomAttributeBuilder(ConstructorInfo, Object(), PropertyInfo(), Object())

Initializes an instance of the CustomAttributeBuilder class given the constructor for the custom attribute, the arguments to the constructor, and a set of named property or value pairs.

System_CAPS_pubmethodCustomAttributeBuilder(ConstructorInfo, Object(), PropertyInfo(), Object(), FieldInfo(), Object())

Initializes an instance of the CustomAttributeBuilder class given the constructor for the custom attribute, the arguments to the constructor, a set of named property or value pairs, and a set of named field or value pairs.

NameDescription
System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubinterfaceSystem_CAPS_privmethod_CustomAttributeBuilder.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.

System_CAPS_pubinterfaceSystem_CAPS_privmethod_CustomAttributeBuilder.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can then be used to get the type information for an interface.

System_CAPS_pubinterfaceSystem_CAPS_privmethod_CustomAttributeBuilder.GetTypeInfoCount(UInt32)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).

System_CAPS_pubinterfaceSystem_CAPS_privmethod_CustomAttributeBuilder.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.

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
      Get
         Return creator
      End Get
   End Property


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

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
      Get
         Return dateUpdated
      End Get
   End Property


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

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, _
							AssemblyBuilderAccess.Run)

      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", _
							TypeAttributes.Public)

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

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

      myTypeBuilder.SetCustomAttribute(myCABuilder)

      ' 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()})

      myMethodBuilder.SetCustomAttribute(myCABuilder2)

      Dim myIL As ILGenerator = myMethodBuilder.GetILGenerator()

      myIL.EmitWriteLine("Hello, world!")
      myIL.Emit(OpCodes.Ret)

      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("---")

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

End Class 'MethodBuilderCustomAttributesDemo

.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 8.0

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

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