ConstructorBuilder.SetCustomAttribute Method

Definition

Namespace:

System.Reflection.Emit

Assemblies:

netstandard.dll, System.Reflection.Emit.dll

Sets a custom attribute.

Overloads

SetCustomAttribute(CustomAttributeBuilder)	Set a custom attribute using a custom attribute builder.
SetCustomAttribute(ConstructorInfo, Byte[])	Set a custom attribute using a specified custom attribute blob.

SetCustomAttribute(CustomAttributeBuilder)

Source:

ConstructorBuilder.cs

Set a custom attribute using a custom attribute builder.

C#

public void SetCustomAttribute(System.Reflection.Emit.CustomAttributeBuilder customBuilder);

Parameters

customBuilder

CustomAttributeBuilder

An instance of a helper class to define the custom attribute.

Exceptions

ArgumentNullException

customBuilder is null.

Examples

The following code sample illustrates the use of SetCustomAttribute of the context of a ConstructorBuilder, passing a CustomAttributeBuilder.

C#

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

[AttributeUsage(AttributeTargets.All, AllowMultiple = false)]
public class MyAttribute : Attribute
{
   public String myString;
   public int myInteger;
   public MyAttribute(String myString, int myInteger)
   {
      this.myString = myString;
      this.myInteger = myInteger;
   }
}

public class MyConstructorBuilder
{
   public static void Main()
   {
      Type myHelloworld = MyCreateCallee(Thread.GetDomain());
      ConstructorInfo myConstructor = myHelloworld.GetConstructor(new Type[]{typeof(String)});
      object[] myAttributes1 = myConstructor.GetCustomAttributes(true);
      Console.WriteLine("MyAttribute custom attribute contains  ");
      for(int index=0; index < myAttributes1.Length; index++)
      {
         if(myAttributes1[index] is MyAttribute)
         {
            Console.WriteLine("The value of myString is : "
                                       + ((MyAttribute)myAttributes1[index]).myString);
            Console.WriteLine("The value of myInteger is : "
                                       + ((MyAttribute)myAttributes1[index]).myInteger);
         }
      }
   }

   private static Type MyCreateCallee(AppDomain domain)
   {
      AssemblyName myAssemblyName = new AssemblyName();
      myAssemblyName.Name = "EmittedAssembly";
      // Define a dynamic assembly in the current application domain.
      AssemblyBuilder myAssembly =
                  domain.DefineDynamicAssembly(myAssemblyName,AssemblyBuilderAccess.Run);
      // Define a dynamic module in this assembly.
      ModuleBuilder myModuleBuilder = myAssembly.DefineDynamicModule("EmittedModule");
       // Construct a 'TypeBuilder' given the name and attributes.
      TypeBuilder myTypeBuilder = myModuleBuilder.DefineType("HelloWorld",
         TypeAttributes.Public);
      // Define a constructor of the dynamic class.
      ConstructorBuilder myConstructor = myTypeBuilder.DefineConstructor(
               MethodAttributes.Public, CallingConventions.Standard, new Type[]{typeof(String)});
      ILGenerator myILGenerator = myConstructor.GetILGenerator();
      myILGenerator.Emit(OpCodes.Ldstr, "Constructor is invoked");
      myILGenerator.Emit(OpCodes.Ldarg_1);
      MethodInfo myMethodInfo =
                     typeof(Console).GetMethod("WriteLine",new Type[]{typeof(string)});
      myILGenerator.Emit(OpCodes.Call, myMethodInfo);
      myILGenerator.Emit(OpCodes.Ret);
      Type myType = typeof(MyAttribute);
      ConstructorInfo myConstructorInfo = myType.GetConstructor(new Type[2]{typeof(String), typeof(int)});
      CustomAttributeBuilder attributeBuilder =
         new CustomAttributeBuilder(myConstructorInfo, new object[2]{"Hello", 2});
      try
      {
         myConstructor.SetCustomAttribute(attributeBuilder);
      }
      catch(ArgumentNullException ex)
      {
         Console.WriteLine("The following exception has occurred : "+ex.Message);
      }
      catch(Exception ex)
      {
         Console.WriteLine("The following exception has occurred : "+ex.Message);
      }
      return myTypeBuilder.CreateType();
   }
}

SetCustomAttribute(ConstructorInfo, Byte[])

Source:

ConstructorBuilder.cs

Set a custom attribute using a specified custom attribute blob.

C#

public void SetCustomAttribute(System.Reflection.ConstructorInfo con, byte[] binaryAttribute);

Parameters

con

ConstructorInfo

The constructor for the custom attribute.

binaryAttribute

Byte[]

A byte blob representing the attributes.

Exceptions

ArgumentNullException

con or binaryAttribute is null.

Examples

The following code sample illustrates the use of SetCustomAttribute of the context of a ConstructorBuilder, passing a byte blob.

C#

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

[AttributeUsage(AttributeTargets.All, AllowMultiple = false)]
public class MyAttribute : Attribute
{
   public bool myBoolean;

   public MyAttribute(bool myBoolean)
   {
      this.myBoolean = myBoolean;
   }
}

public class MyConstructorBuilder
{
   public static void Main()
   {
      Type myHelloworld = MyCreateCallee(Thread.GetDomain());
      ConstructorInfo myConstructor = myHelloworld.GetConstructor(new Type[]{typeof(String)});
      object[] myAttributes1 = myConstructor.GetCustomAttributes(true);
      Console.WriteLine("MyAttribute custom attribute contains  ");
      for(int index=0; index < myAttributes1.Length; index++)
      {
         if(myAttributes1[index] is MyAttribute)
         {
            Console.WriteLine("myBoolean : " + ((MyAttribute)myAttributes1[index]).myBoolean);
         }
      }
   }

   private static Type MyCreateCallee(AppDomain domain)
   {
      AssemblyName myAssemblyName = new AssemblyName();
      myAssemblyName.Name = "EmittedAssembly";
      // Define a dynamic assembly in the current application domain.
      AssemblyBuilder myAssembly =
                  domain.DefineDynamicAssembly(myAssemblyName,AssemblyBuilderAccess.Run);
      // Define a dynamic module in this assembly.
      ModuleBuilder myModuleBuilder = myAssembly.DefineDynamicModule("EmittedModule");
      // Construct a 'TypeBuilder' given the name and attributes.
      TypeBuilder myTypeBuilder = myModuleBuilder.DefineType("HelloWorld",
         TypeAttributes.Public);
      // Define a constructor of the dynamic class.
      ConstructorBuilder myConstructor = myTypeBuilder.DefineConstructor(
               MethodAttributes.Public, CallingConventions.Standard, new Type[]{typeof(String)});
      ILGenerator myILGenerator = myConstructor.GetILGenerator();
      myILGenerator.Emit(OpCodes.Ldstr, "Constructor is invoked");
      myILGenerator.Emit(OpCodes.Ldarg_1);
      MethodInfo myMethodInfo =
                     typeof(Console).GetMethod("WriteLine",new Type[]{typeof(string)});
      myILGenerator.Emit(OpCodes.Call, myMethodInfo);
      myILGenerator.Emit(OpCodes.Ret);
      Type myType = typeof(MyAttribute);
      ConstructorInfo myConstructorInfo = myType.GetConstructor(new Type[]{typeof(bool)});
      try
      {
         myConstructor.SetCustomAttribute(myConstructorInfo, new byte[]{01,00,01});
      }
      catch(ArgumentNullException ex)
      {
         Console.WriteLine("The following exception has occurred : "+ex.Message);
      }
      catch(Exception ex)
      {
         Console.WriteLine("The following exception has occurred : "+ex.Message);
      }
      return myTypeBuilder.CreateType();
   }
}

Remarks

For information on how to format binaryAttribute, see the metadata specification in Partition II of the Common Language Infrastructure (CLI) specification.