CustomAttributeBuilder Class
Helps build custom attributes.
For a list of all members of this type, see CustomAttributeBuilder Members.
System.Object
System.Reflection.Emit.CustomAttributeBuilder
[Visual Basic] Public Class CustomAttributeBuilder [C#] public class CustomAttributeBuilder [C++] public __gc class CustomAttributeBuilder [JScript] public class CustomAttributeBuilder
Thread Safety
Reflection Emit is thread-safe when using assemblies that were created with the AppDomain.DefineDynamicAssembly method with the Boolean parameter isSynchronized set to true.
Remarks
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.
Example
[Visual Basic, C#, C++] The following code sample illustrates the use of CustomAttributeBuilder.
[Visual Basic] Imports System Imports System.Threading Imports System.Reflection Imports System.Reflection.Emit _ ' We will apply this custom attribute to our dynamic type. Public Class ClassCreator Inherits Attribute Private creator As String Public ReadOnly Property GetCreator() As String Get Return creator End Get End Property Public Sub New(name As String) Me.creator = name End Sub 'New End Class 'ClassCreator _ ' We will apply this dynamic attribute to our dynamic method. Public Class DateLastUpdated Inherits Attribute Private dateUpdated As String Public ReadOnly Property GetDateUpdated() As String Get Return dateUpdated End Get End Property Public Sub New(theDate As String) Me.dateUpdated = theDate End Sub 'New End Class 'DateLastUpdated _ Class MethodBuilderCustomAttributesDemo Public Shared Function BuildTypeWithCustomAttributesOnMethod() As Type Dim currentDomain As AppDomain = Thread.GetDomain() Dim myAsmName As New AssemblyName() myAsmName.Name = "MyAssembly" Dim myAsmBuilder As AssemblyBuilder = currentDomain.DefineDynamicAssembly(myAsmName, _ AssemblyBuilderAccess.Run) Dim myModBuilder As ModuleBuilder = myAsmBuilder.DefineDynamicModule("MyModule") ' First, we'll build a type with a custom attribute attached. Dim myTypeBuilder As TypeBuilder = myModBuilder.DefineType("MyType", _ TypeAttributes.Public) Dim ctorParams() As Type = {GetType(String)} Dim classCtorInfo As ConstructorInfo = GetType(ClassCreator).GetConstructor(ctorParams) Dim myCABuilder As New CustomAttributeBuilder(classCtorInfo, _ New Object() {"Joe Programmer"}) myTypeBuilder.SetCustomAttribute(myCABuilder) ' Now, let's build a method and add a custom attribute to it. Dim myMethodBuilder As MethodBuilder = myTypeBuilder.DefineMethod("HelloWorld", _ MethodAttributes.Public, Nothing, New Type() {}) ctorParams = New Type() {GetType(String)} classCtorInfo = GetType(DateLastUpdated).GetConstructor(ctorParams) Dim myCABuilder2 As New CustomAttributeBuilder(classCtorInfo, _ New Object() {DateTime.Now.ToString()}) myMethodBuilder.SetCustomAttribute(myCABuilder2) Dim myIL As ILGenerator = myMethodBuilder.GetILGenerator() myIL.EmitWriteLine("Hello, world!") myIL.Emit(OpCodes.Ret) Return myTypeBuilder.CreateType() End Function 'BuildTypeWithCustomAttributesOnMethod Public Shared Sub Main() Dim myType As Type = BuildTypeWithCustomAttributesOnMethod() Dim myInstance As Object = Activator.CreateInstance(myType) Dim customAttrs As Object() = myType.GetCustomAttributes(True) Console.WriteLine("Custom Attributes for Type 'MyType':") Dim attrVal As Object = Nothing Dim customAttr As Object For Each customAttr In customAttrs attrVal = GetType(ClassCreator).InvokeMember("GetCreator", _ BindingFlags.GetProperty, _ Nothing, customAttr, New Object() {}) Console.WriteLine("-- Attribute: [{0} = ""{1}""]", customAttr, attrVal) Next customAttr Console.WriteLine("Custom Attributes for Method 'HelloWorld()' in 'MyType':") customAttrs = myType.GetMember("HelloWorld")(0).GetCustomAttributes(True) For Each customAttr In customAttrs attrVal = GetType(DateLastUpdated).InvokeMember("GetDateUpdated", _ BindingFlags.GetProperty, _ Nothing, customAttr, New Object() {}) Console.WriteLine("-- Attribute: [{0} = ""{1}""]", customAttr, attrVal) Next customAttr Console.WriteLine("---") Console.WriteLine(myType.InvokeMember("HelloWorld", BindingFlags.InvokeMethod, _ Nothing, myInstance, New Object() {})) End Sub 'Main End Class 'MethodBuilderCustomAttributesDemo [C#] 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[] { })); } } [C++] #using <mscorlib.dll> using namespace System; using namespace System::Threading; using namespace System::Reflection; using namespace System::Reflection::Emit; // We will apply this custom attribute to our dynamic type. public __gc class ClassCreator : public Attribute { private: String* creator; public: __property String* get_Creator() { return creator; } public: ClassCreator(String* name) { this->creator = name; } }; // We will apply this dynamic attribute to our dynamic method. public __gc class DateLastUpdated : public Attribute { private: String* dateUpdated; public: __property String* get_DateUpdated() { return dateUpdated; } public: DateLastUpdated(String* theDate) { this->dateUpdated = theDate; } }; Type* BuildTypeWithCustomAttributesOnMethod() { AppDomain* currentDomain = Thread::GetDomain(); AssemblyName* myAsmName = new AssemblyName(); myAsmName->Name = S"MyAssembly"; AssemblyBuilder* myAsmBuilder = currentDomain->DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess::Run); ModuleBuilder* myModBuilder = myAsmBuilder->DefineDynamicModule(S"MyModule"); // First, we'll build a type with a custom attribute attached. TypeBuilder* myTypeBuilder = myModBuilder->DefineType(S"MyType", TypeAttributes::Public); Type* temp6 [] = {__typeof(String)}; Type* ctorParams[] = temp6; ConstructorInfo* classCtorInfo = __typeof(ClassCreator)->GetConstructor(ctorParams); Object* temp0 [] = {S"Joe Programmer"}; CustomAttributeBuilder* myCABuilder = new CustomAttributeBuilder(classCtorInfo, temp0); myTypeBuilder->SetCustomAttribute(myCABuilder); // Now, let's build a method and add a custom attribute to it. Type* temp1 [] = new Type*[0]; MethodBuilder* myMethodBuilder = myTypeBuilder->DefineMethod(S"HelloWorld", MethodAttributes::Public, 0, temp1); Type* temp7 [] = {__typeof(String)}; ctorParams = temp7; classCtorInfo = __typeof(DateLastUpdated)->GetConstructor(ctorParams); Object* temp2 [] = {DateTime::Now.ToString()}; CustomAttributeBuilder* myCABuilder2 = new CustomAttributeBuilder(classCtorInfo, temp2); myMethodBuilder->SetCustomAttribute(myCABuilder2); ILGenerator* myIL = myMethodBuilder->GetILGenerator(); myIL->EmitWriteLine(S"Hello, world!"); myIL->Emit(OpCodes::Ret); return myTypeBuilder->CreateType(); } int main() { Type* myType = BuildTypeWithCustomAttributesOnMethod(); Object* myInstance = Activator::CreateInstance(myType); Object* customAttrs[] = myType->GetCustomAttributes(true); Console::WriteLine(S"Custom Attributes for Type 'MyType':"); Object* attrVal = 0; System::Collections::IEnumerator* myEnum = customAttrs->GetEnumerator(); while (myEnum->MoveNext()) { Object* customAttr = __try_cast<Object*>(myEnum->Current); Object* temp3 [] = new Object*[0]; attrVal = __typeof(ClassCreator)->InvokeMember(S"Creator", BindingFlags::GetProperty, 0, customAttr, temp3); Console::WriteLine(S"-- Attribute: [{0} = \"{1}\"]", customAttr, attrVal); } Console::WriteLine(S"Custom Attributes for Method 'HelloWorld()' in 'MyType':"); customAttrs = myType->GetMember(S"HelloWorld")[0]->GetCustomAttributes(true); System::Collections::IEnumerator* myEnum2 = customAttrs->GetEnumerator(); while (myEnum2->MoveNext()) { Object* customAttr = __try_cast<Object*>(myEnum2->Current); Object* temp4 [] = new Object*[0]; attrVal = __typeof(DateLastUpdated)->InvokeMember(S"DateUpdated", BindingFlags::GetProperty, 0, customAttr, temp4); Console::WriteLine(S"-- Attribute: [{0} = \"{1}\"]", customAttr, attrVal); } Console::WriteLine(S"---"); Object* temp5 [] = new Object*[0]; Console::WriteLine(myType->InvokeMember(S"HelloWorld", BindingFlags::InvokeMethod, 0, myInstance, temp5)); }
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Requirements
Namespace: System.Reflection.Emit
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family
Assembly: Mscorlib (in Mscorlib.dll)
See Also
CustomAttributeBuilder Members | System.Reflection.Emit Namespace