This documentation is archived and is not being maintained.

AssemblyBuilder.SetCustomAttribute Method (CustomAttributeBuilder)

Set a custom attribute on this assembly using a custom attribute builder.

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

public void SetCustomAttribute(
	CustomAttributeBuilder customBuilder


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


con is null.


The caller does not have the required permission.


SetCustomAttribute cannot be used to set declarative security attributes. Use one of the overloads of DefineDynamicAssembly that takes required, optional, and refused permissions.


Starting with the .NET Framework version 2.0 Service Pack 1, this member no longer requires ReflectionPermission with the ReflectionPermissionFlag.ReflectionEmit flag. (See Security Issues in Reflection Emit.) To use this functionality, your application should target the .NET Framework version 3.5 or later.

The following code sample illustrates the use of SetCustomAttribute within AssemblyBuilder, using a CustomAttributeBuilder.

[AttributeUsage(AttributeTargets.All, AllowMultiple = false)]
public class MyAttribute : Attribute
   public String s;
   public int x;

   public MyAttribute(String s, int x)
      this.s = s;
      this.x = x;

class MyApplication
   public static void Main()
      Type customAttribute = CreateCallee(Thread.GetDomain());
      object[] attributes = customAttribute.Assembly.GetCustomAttributes(true);
      Console.WriteLine("MyAttribute custom attribute contains : ");
      for(int index=0; index < attributes.Length; index++)
         if(attributes[index] is MyAttribute)
            Console.WriteLine("s : " + ((MyAttribute)attributes[index]).s);
            Console.WriteLine("x : " + ((MyAttribute)attributes[index]).x);

   private static Type CreateCallee(AppDomain domain)
      AssemblyName myAssemblyName = new AssemblyName();
      myAssemblyName.Name = "EmittedAssembly";
      AssemblyBuilder myAssembly = domain.DefineDynamicAssembly(myAssemblyName,
      Type myType = typeof(MyAttribute);
      ConstructorInfo infoConstructor = myType.GetConstructor(new Type[2]{typeof(String), typeof(int)});
      CustomAttributeBuilder attributeBuilder =
         new CustomAttributeBuilder(infoConstructor, new object[2]{"Hello", 2});
      ModuleBuilder myModule = myAssembly.DefineDynamicModule("EmittedModule");
      // Define a public class named "HelloWorld" in the assembly.
      TypeBuilder helloWorldClass = myModule.DefineType("HelloWorld", TypeAttributes.Public);


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.