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CustomAttributeBuilder Class

Represents a custom attribute in a form that can be attached to a type or member that is being emitted.

System.Object
  System.Reflection.Emit.CustomAttributeBuilder

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

[ClassInterfaceAttribute(ClassInterfaceType.None)]
[ComVisibleAttribute(true)]
public class CustomAttributeBuilder

The CustomAttributeBuilder type exposes the following members.

  NameDescription
Public methodCustomAttributeBuilder(ConstructorInfo, Object[])Initializes a new instance of the CustomAttributeBuilder class given the constructor for the custom attribute and the arguments to the constructor.
Public methodCustomAttributeBuilder(ConstructorInfo, Object[], FieldInfo[], Object[])Initializes a new 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.
Public methodCustomAttributeBuilder(ConstructorInfo, Object[], PropertyInfo[], Object[])Initializes a new 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.
Public methodCustomAttributeBuilder(ConstructorInfo, Object[], PropertyInfo[], Object[], FieldInfo[], Object[])Initializes a new 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.
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  NameDescription
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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Use the CustomAttributeBuilder object returned by the constructor to attach a custom attribute to a dynamic type or member. Associate the custom attribute 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 the AssemblyBuilder.SetCustomAttribute method to attach the AssemblyCultureAttribute to a dynamic assembly.

The following code example 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 Example
{

   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 Demo(System.Windows.Controls.TextBlock outputBlock)
   {

      Type myType = BuildTypeWithCustomAttributesOnMethod();

      object myInstance = Activator.CreateInstance(myType);

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

      outputBlock.Text += "Custom Attributes for Type 'MyType':" + "\n";

      object attrVal = null;

      foreach (object customAttr in customAttrs)
      {
         attrVal = typeof(ClassCreator).InvokeMember("Creator",
                    BindingFlags.GetProperty,
                    null, customAttr, new object[] { });
         outputBlock.Text += String.Format("-- Attribute: [{0} = \"{1}\"]", customAttr, attrVal) + "\n";
      }

      outputBlock.Text += "Custom Attributes for Method 'HelloWorld()' in 'MyType':" + "\n";

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

      foreach (object customAttr in customAttrs)
      {
         attrVal = typeof(DateLastUpdated).InvokeMember("DateUpdated",
                    BindingFlags.GetProperty,
                    null, customAttr, new object[] { });
         outputBlock.Text += String.Format("-- Attribute: [{0} = \"{1}\"]", customAttr, attrVal) + "\n";
      }

      outputBlock.Text += "---" + "\n";

      outputBlock.Text += myType.InvokeMember("HelloWorld",
              BindingFlags.InvokeMethod,
              null, myInstance, new object[] { }) + "\n";


   }

}



Silverlight

Supported in: 5, 4, 3

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

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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