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 : _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.


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 
   {
	get
	{
	   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
   {
   	get
	{
	   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",
						TypeAttributes.Public);

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

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

	myTypeBuilder.SetCustomAttribute(myCABuilder);

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

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

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

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

	myMethodBuilder.SetCustomAttribute(myCABuilder2);

	ILGenerator myIL = myMethodBuilder.GetILGenerator();

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

	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", 
					  BindingFlags.GetProperty,
					  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", 
					  BindingFlags.GetProperty,
					  null, customAttr, new object[] { });
	   Console.WriteLine("-- Attribute: [{0} = \"{1}\"]", customAttr, attrVal);
        }

	Console.WriteLine("---");

	Console.WriteLine(myType.InvokeMember("HelloWorld",
			  BindingFlags.InvokeMethod,
			  null, myInstance, new object[] { }));


   }

}

Universal Windows Platform
Available since 10
.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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