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CustomAttributeBuilder Class

Helps build custom attributes.

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

[ComVisibleAttribute(true)] 
[ClassInterfaceAttribute(ClassInterfaceType.None)] 
public class CustomAttributeBuilder : _CustomAttributeBuilder
/** @attribute ComVisibleAttribute(true) */ 
/** @attribute ClassInterfaceAttribute(ClassInterfaceType.None) */ 
public class CustomAttributeBuilder implements _CustomAttributeBuilder
ComVisibleAttribute(true) 
ClassInterfaceAttribute(ClassInterfaceType.None) 
public class CustomAttributeBuilder implements _CustomAttributeBuilder

NoteNote

The HostProtectionAttribute attribute applied to this class 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 to 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[] { }));
						   
	
   }

}


import System.*;
import System.Threading.*;
import System.Reflection.*;
import System.Reflection.Emit.*;

// We will apply this custom attribute to our dynamic type.
public class ClassCreator extends Attribute
{
    private String creator;

    /** @property 
     */
    public String get_Creator()
    {
        return creator ;
    } //get_Creator

    public ClassCreator(String name) 
    {
        this.creator = name;
    } //ClassCreator
} //ClassCreator

// We will apply this dynamic attribute to our dynamic method.
public class DateLastUpdated extends Attribute
{
    private String dateUpdated;
    /** @property 
     */
    public String get_DateUpdated()
    {
        return dateUpdated ;
    } //get_DateUpdated

    public DateLastUpdated(String theDate) 
    {
        this.dateUpdated = theDate;
    } //DateLastUpdated
} //DateLastUpdated

class MethodBuilderCustomAttributesDemo
{
    public static Type BuildTypeWithCustomAttributesOnMethod() 
    {
        AppDomain currentDomain = System.Threading.Thread.GetDomain();
        AssemblyName myAsmName = new AssemblyName();
        myAsmName.set_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[]{String.class.ToType()};
        ConstructorInfo classCtorInfo = 
            ClassCreator.class.ToType().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[]{String.class.ToType()};
        classCtorInfo =
            DateLastUpdated.class.ToType().GetConstructor(ctorParams);
        CustomAttributeBuilder myCABuilder2 = new CustomAttributeBuilder(
            classCtorInfo, new Object[]{DateTime.get_Now().ToString()});
        myMethodBuilder.SetCustomAttribute(myCABuilder2);
        ILGenerator myIL = myMethodBuilder.GetILGenerator();
        myIL.EmitWriteLine("Hello, world!");
        myIL.Emit(OpCodes.Ret);      
        return myTypeBuilder.CreateType() ;
    } //BuildTypeWithCustomAttributesOnMethod

    public static void main(String[] args)
    {
        Type myType = BuildTypeWithCustomAttributesOnMethod();      
        Object myInstance = Activator.CreateInstance(myType);      
        Object customAttrs[] = myType.GetCustomAttributes(true);      
        Console.WriteLine("Custom Attributes for Type 'MyType':");      
        Object attrVal = null;
        for (int iCtr=0; iCtr < customAttrs.length; iCtr++) {
            Object customAttr = customAttrs[iCtr];
            attrVal = ClassCreator.class.ToType().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);
        for(int iCtr = 0; iCtr < customAttrs.length; iCtr++) {
            Object customAttr = customAttrs[iCtr];
            attrVal = DateLastUpdated.class.ToType().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[] {}));
    } //main
} //MethodBuilderCustomAttributesDemo

System.Object
  System.Reflection.Emit.CustomAttributeBuilder

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 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

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