System.Reflection.Emitについて (3)(属性付きのクラス) (AssemblyBuilder, ModuleBuilder, TypeBuilder, ILGenerator, MSIL, PropertyBuilder, MethodBuilder, CustomAttributeBuilder)

引き続き属性設定の実装の仕方のサンプルです。

#region Emitのサンプル3

    public class EmitSample3 : IExecutable{

        [AttributeUsage(AttributeTargets.Class)]
        public class IsDynamicTypeAttribute : Attribute{
        }

        [AttributeUsage(AttributeTargets.Class)]
        public class CreatorAttribute : Attribute{
            public CreatorAttribute(string name){
                CreatorName = name;
            }

            public string CreatorName{
                get;
                set;
            }
        }

        private static readonly string ASM_NAME = "DynamicTypes";
        private static readonly string MOD_NAME = string.Format("{0}.dll", ASM_NAME);

        public void Execute(){
            AssemblyName    asmName     = new AssemblyName{Name=ASM_NAME};
            AppDomain       appDomain   = AppDomain.CurrentDomain;
            AssemblyBuilder asmBuilder  = appDomain.DefineDynamicAssembly(asmName, AssemblyBuilderAccess.RunAndSave);
            ModuleBuilder   modBuilder  = asmBuilder.DefineDynamicModule(ASM_NAME, MOD_NAME);
            TypeBuilder     typeBuilder = modBuilder.DefineType("AttrTest", TypeAttributes.Public, typeof(object), Type.EmptyTypes);

            //
            // 型に対してカスタム属性を付加する。
            // 複数の属性を付ける場合は、AddAttributeメソッド内のようにSetCustomAttributeメソッドを
            // 複数呼びます。
            //
            AddAttribute(typeBuilder, typeof(IsDynamicTypeAttribute), Type.EmptyTypes,              new object[]{});
            AddAttribute(typeBuilder, typeof(CreatorAttribute),       new Type[]{ typeof(string) }, new object[]{ "gsf.zero1" });

            Type   type = typeBuilder.CreateType();
            object obj  = Activator.CreateInstance(type);

            object[] attrs = type.GetCustomAttributes(true);
            if(attrs.Length > 0){
                foreach(object attr in attrs){
                    Console.WriteLine(attr);

                    if(attr is CreatorAttribute){
                        Console.WriteLine("\tName={0}", (attr as CreatorAttribute).CreatorName);
                    }
                }
            }

            asmBuilder.Save(MOD_NAME);
        }

        private void AddAttribute(TypeBuilder typeBuilder, Type attrType, Type[] attrCtorParamTypes, object[] attrCtorParams){
            ConstructorInfo ctorInfo = attrType.GetConstructor(attrCtorParamTypes);

            if(ctorInfo != null){
                CustomAttributeBuilder attrBuilder = new CustomAttributeBuilder(ctorInfo, attrCtorParams);
                typeBuilder.SetCustomAttribute(attrBuilder);
            }
        }
    }
#endregion