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CustomAttributeBuilder Class

Helps build custom attributes.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, MayLeakOnAbort = true)]
public class CustomAttributeBuilder : _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.

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

// We will apply this custom attribute to our dynamic type. 
public class ClassCreator: Attribute

   private string creator;
   public string Creator 
	   return creator;

   public ClassCreator(string name)
      this.creator = name;


// We will apply this dynamic attribute to our dynamic method. 
public class DateLastUpdated: Attribute

   private string dateUpdated;
   public string DateUpdated
	   return dateUpdated;

   public DateLastUpdated(string theDate)
	this.dateUpdated = theDate;


class MethodBuilderCustomAttributesDemo


   public static Type BuildTypeWithCustomAttributesOnMethod()
	AppDomain currentDomain = Thread.GetDomain();
	AssemblyName myAsmName = new AssemblyName();
	myAsmName.Name = "MyAssembly";

	AssemblyBuilder myAsmBuilder = currentDomain.DefineDynamicAssembly(
				       myAsmName, AssemblyBuilderAccess.Run);

	ModuleBuilder myModBuilder = myAsmBuilder.DefineDynamicModule("MyModule");

	// First, we'll build a type with a custom attribute attached.

	TypeBuilder myTypeBuilder = myModBuilder.DefineType("MyType",
	Type[] ctorParams = new Type[] { typeof(string) };
	ConstructorInfo classCtorInfo = typeof(ClassCreator).GetConstructor(ctorParams);

	CustomAttributeBuilder myCABuilder = new CustomAttributeBuilder(
						new object[] { "Joe Programmer" });


	// Now, let's build a method and add a custom attribute to it.

	MethodBuilder myMethodBuilder = myTypeBuilder.DefineMethod("HelloWorld",
					new Type[] { });

	ctorParams = new Type[] { typeof(string) };
	classCtorInfo = typeof(DateLastUpdated).GetConstructor(ctorParams);

	CustomAttributeBuilder myCABuilder2 = new CustomAttributeBuilder(
						new object[] { DateTime.Now.ToString() });


	ILGenerator myIL = myMethodBuilder.GetILGenerator();

	myIL.EmitWriteLine("Hello, world!");

	return myTypeBuilder.CreateType();

   public static void Main() 

	Type myType = BuildTypeWithCustomAttributesOnMethod();

	object myInstance = Activator.CreateInstance(myType);

	object[] customAttrs = myType.GetCustomAttributes(true);

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

	object attrVal = null;

	foreach (object customAttr in customAttrs) 
	   attrVal = typeof(ClassCreator).InvokeMember("Creator", 
					  null, customAttr, new object[] { });
	   Console.WriteLine("-- Attribute: [{0} = \"{1}\"]", customAttr, attrVal);

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

	customAttrs = myType.GetMember("HelloWorld")[0].GetCustomAttributes(true);	

	foreach (object customAttr in customAttrs) 
	   attrVal = typeof(DateLastUpdated).InvokeMember("DateUpdated", 
					  null, customAttr, new object[] { });
	   Console.WriteLine("-- Attribute: [{0} = \"{1}\"]", customAttr, attrVal);


			  null, myInstance, new object[] { }));



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

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