EnumBuilder.SetCustomAttribute Method

Parameters

• customBuilder
  Type: System.Reflection.Emit.CustomAttributeBuilder
  An instance of a helper class to define the custom attribute.

Imports System.Reflection
Imports System.Reflection.Emit

<AttributeUsage(AttributeTargets.All, AllowMultiple:=False)> _
Public Class MyAttribute
   Inherits Attribute
   Private myBoolValue As Boolean

   Public ReadOnly Property MyBool As Boolean
      Get
         Return myBoolValue
      End Get
   End Property

   Public Sub New(ByVal myBool As Boolean)
      myBoolValue = myBool
   End Sub 
End Class 

Class Example

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      ' Get the current application domain.
      Dim currentDomain As AppDomain = AppDomain.CurrentDomain

      ' Create a dynamic assembly in the current application domain, 
      ' and allow it to be executed.
      Dim aName As AssemblyName = New AssemblyName("TempAssembly")
      Dim ab As AssemblyBuilder = currentDomain.DefineDynamicAssembly( _
          aName, AssemblyBuilderAccess.Run)

      ' Define a dynamic module in "TempAssembly" assembly. The module can
      ' have the same name as the assembly.
      Dim mb As ModuleBuilder = _
          ab.DefineDynamicModule(aName.Name)

      ' Define a public enumeration with the name "Elevation" and an 
      ' underlying type of Integer.
      Dim eb As EnumBuilder = _
          mb.DefineEnum("Elevation", TypeAttributes.Public, GetType(Integer))

      ' Define two members, "High" and "Low".
      eb.DefineLiteral("Low", 0)
      eb.DefineLiteral("High", 1)

      ' To set a custom attribute, first get the constructor for the attribute.
      ' Use the constructor and an array of arguments for the constructor to
      ' create a CustomAttributeBuilder. Finally, use the CustomAttributeBuilder
      ' to set the attribute on the enumeration. 
      Dim attrType As Type = GetType(MyAttribute)
      Dim attrCtor As ConstructorInfo = _
         attrType.GetConstructor(New Type() {GetType(Boolean)})
      Dim attrBuilder As New CustomAttributeBuilder( _
         attrCtor, New Object() { True })
      eb.SetCustomAttribute(attrBuilder)

      ' Create the type.
      Dim finished As Type = eb.CreateType()

      For Each fi As FieldInfo in finished.GetFields()
         outputBlock.Text &= String.Format("{0}.{1} = {2}" & vbCrLf, _
            finished.Name, fi.Name, fi.GetRawConstantValue())
      Next

      ' Read the attributes and display them.
      outputBlock.Text &= vbCrLf & "Custom attributes: " & vbCrLf
      For Each attr As Object In finished.GetCustomAttributes(True)
         outputBlock.Text &= attr.ToString() & vbCrLf
         If TypeOf attr Is MyAttribute Then
            outputBlock.Text &= String.Format("    MyBool: {0}" & vbCrLf, _
               CType(attr, MyAttribute).MyBool.ToString())
         End If
      Next

   End Sub
End Class

' This code example produces output similar to the following:
'
'Elevation.Low = 0
'Elevation.High = 1 
'
'Custom attributes:
'SilverlightApplication.MyAttribute
'    MyBool: True

using System;
using System.Reflection;
using System.Reflection.Emit;

[AttributeUsage(AttributeTargets.All, AllowMultiple = false)]
public class MyAttribute : Attribute
{
   private bool myBoolValue;

   public bool MyBool { get { return myBoolValue; }}   

   public MyAttribute(bool myBool)
   {
      this.myBoolValue = myBool;
   }
}

class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // Get the current application domain.
      AppDomain currentDomain = AppDomain.CurrentDomain;

      // Create a dynamic assembly in the current application domain, 
      // and allow it to be executed.
      AssemblyName aName = new AssemblyName("TempAssembly");
      AssemblyBuilder ab = currentDomain.DefineDynamicAssembly(
          aName, AssemblyBuilderAccess.Run);

      // Define a dynamic module in "TempAssembly" assembly. The module can
      // have the same name as the assembly.
      ModuleBuilder mb = ab.DefineDynamicModule(aName.Name);

      // Define a public enumeration with the name "Elevation" and an 
      // underlying type of Integer.
      EnumBuilder eb = mb.DefineEnum("Elevation", TypeAttributes.Public, typeof(int));

      // Define two members, "High" and "Low".
      eb.DefineLiteral("Low", 0);
      eb.DefineLiteral("High", 1);

      // To set a custom attribute, first get the constructor for the attribute.
      // Use the constructor and an array of arguments for the constructor to
      // create a CustomAttributeBuilder. Finally, use the CustomAttributeBuilder
      // to set the attribute on the enumeration. 
      Type attrType = typeof(MyAttribute);
      ConstructorInfo attrCtor = 
         attrType.GetConstructor(new Type[] {typeof(bool)});
      CustomAttributeBuilder attrBuilder =
         new CustomAttributeBuilder(attrCtor, new Object[] { true });
      eb.SetCustomAttribute(attrBuilder);

      // Create the type.
      Type finished = eb.CreateType();

      foreach (FieldInfo fi in finished.GetFields())
      {
         outputBlock.Text += String.Format("{0}.{1} = {2}\n", 
            finished.Name, fi.Name, fi.GetRawConstantValue());
      }

      // Read the attributes and display them.
      outputBlock.Text += "\nCustom attributes: \n";
      foreach (object attr in finished.GetCustomAttributes(true))
      {
         outputBlock.Text += attr.ToString() + "\n";
         if (attr is MyAttribute)
         {
            outputBlock.Text += String.Format("    MyBool: {0}\n",
               ((MyAttribute) attr).MyBool.ToString());
         }
      }
   }
}

/* This code example produces the following output:

Elevation.Low = 0
Elevation.High = 1 

Custom attributes:
MyAttribute
    MyBool: True
 */