EnumBuilder.SetCustomAttribute Method

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Sets a custom attribute using a custom attribute builder.

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

Syntax

'Declaration
Public Sub SetCustomAttribute ( _
    customBuilder As CustomAttributeBuilder _
)

public void SetCustomAttribute(
    CustomAttributeBuilder customBuilder
)

Parameters

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

Exceptions

Exception	Condition
ArgumentNullException	con is nulla null reference (Nothing in Visual Basic).

Examples

The following code sample illustrates the use of SetCustomAttribute in the context of EnumBuilder, passing a CustomAttributeBuilder.

Note:
To run this example, see Building Examples That Use a Demo Method and a TextBlock Control.

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
 */

Version Information

Silverlight

Supported in: 5, 4, 3

Platforms

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

See Also

Reference

EnumBuilder Class

System.Reflection.Emit Namespace