ILGenerator.BeginFinallyBlock Method

Definition

Namespace:

System.Reflection.Emit

Assembly:

System.Reflection.Emit.ILGeneration.dll

Source:

ILGenerator.cs

Begins a finally block in the Microsoft intermediate language (MSIL) instruction stream.

public:
 abstract void BeginFinallyBlock();

public abstract void BeginFinallyBlock ();

abstract member BeginFinallyBlock : unit -> unit

Public MustOverride Sub BeginFinallyBlock ()

Exceptions

NotSupportedException

The MSIL being generated is not currently in an exception block.

Examples

The following code sample illustrates the use of BeginFinallyBlock.

using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;

public ref class ILGenerator_BeginFinallyBlock
{
public:
   static Type^ AddType()
   {
      // Create an assembly.
      AssemblyName^ myAssemblyName = gcnew AssemblyName;
      myAssemblyName->Name = "AdderExceptionAsm";

      // Create dynamic assembly.
      AppDomain^ myAppDomain = Thread::GetDomain();
      AssemblyBuilder^ myAssemblyBuilder = myAppDomain->DefineDynamicAssembly( myAssemblyName, AssemblyBuilderAccess::Run );

      // Create a dynamic module.
      ModuleBuilder^ myModuleBuilder = myAssemblyBuilder->DefineDynamicModule( "AdderExceptionMod" );
      TypeBuilder^ myTypeBuilder = myModuleBuilder->DefineType( "Adder" );
      array<Type^>^adderParams = {int::typeid,int::typeid};

      // Define method to add two numbers.
      MethodBuilder^ myMethodBuilder = myTypeBuilder->DefineMethod( "DoAdd", static_cast<MethodAttributes>(MethodAttributes::Public | MethodAttributes::Static), int::typeid, adderParams );
      ILGenerator^ myAdderIL = myMethodBuilder->GetILGenerator();

      // Create constructor.
      array<Type^>^type1 = {String::typeid};
      ConstructorInfo^ myConstructorInfo = OverflowException::typeid->GetConstructor( type1 );
      MethodInfo^ myExToStrMI = OverflowException::typeid->GetMethod( "ToString" );
      array<Type^>^type2 = {String::typeid,Object::typeid};
      MethodInfo^ myWriteLineMI = Console::typeid->GetMethod( "WriteLine", type2 );

      // Declare local variable.
      LocalBuilder^ myLocalBuilder1 = myAdderIL->DeclareLocal( int::typeid );
      LocalBuilder^ myLocalBuilder2 = myAdderIL->DeclareLocal( OverflowException::typeid );

      // Define label.
      Label myFailedLabel = myAdderIL->DefineLabel();
      Label myEndOfMethodLabel = myAdderIL->DefineLabel();

      // Begin exception block.
      Label myLabel = myAdderIL->BeginExceptionBlock();
      myAdderIL->Emit( OpCodes::Ldarg_0 );
      myAdderIL->Emit( OpCodes::Ldc_I4_S, 10 );
      myAdderIL->Emit( OpCodes::Bgt_S, myFailedLabel );
      myAdderIL->Emit( OpCodes::Ldarg_1 );
      myAdderIL->Emit( OpCodes::Ldc_I4_S, 10 );
      myAdderIL->Emit( OpCodes::Bgt_S, myFailedLabel );
      myAdderIL->Emit( OpCodes::Ldarg_0 );
      myAdderIL->Emit( OpCodes::Ldarg_1 );
      myAdderIL->Emit( OpCodes::Add_Ovf_Un );
      myAdderIL->Emit( OpCodes::Stloc_S, myLocalBuilder1 );
      myAdderIL->Emit( OpCodes::Br_S, myEndOfMethodLabel );
      myAdderIL->MarkLabel( myFailedLabel );
      myAdderIL->Emit( OpCodes::Ldstr, "Cannot accept values over 10 for add." );
      myAdderIL->Emit( OpCodes::Newobj, myConstructorInfo );
      myAdderIL->Emit( OpCodes::Stloc_S, myLocalBuilder2 );
      myAdderIL->Emit( OpCodes::Ldloc_S, myLocalBuilder2 );

      // Throw the exception.
      myAdderIL->ThrowException( OverflowException::typeid );

      // Call 'BeginExceptFilterBlock'.
      myAdderIL->BeginExceptFilterBlock();
      myAdderIL->EmitWriteLine( "Except filter block called." );

      // Call catch block.
      myAdderIL->BeginCatchBlock( nullptr );

      // Call other catch block.
      myAdderIL->BeginCatchBlock( OverflowException::typeid );
      myAdderIL->Emit( OpCodes::Ldstr, "{0}" );
      myAdderIL->Emit( OpCodes::Ldloc_S, myLocalBuilder2 );
      myAdderIL->EmitCall( OpCodes::Callvirt, myExToStrMI, nullptr );
      myAdderIL->EmitCall( OpCodes::Call, myWriteLineMI, nullptr );
      myAdderIL->Emit( OpCodes::Ldc_I4_M1 );
      myAdderIL->Emit( OpCodes::Stloc_S, myLocalBuilder1 );

      // Call finally block.
      myAdderIL->BeginFinallyBlock();
      myAdderIL->EmitWriteLine( "Finally block called." );

      // End the exception block.
      myAdderIL->EndExceptionBlock();
      myAdderIL->MarkLabel( myEndOfMethodLabel );
      myAdderIL->Emit( OpCodes::Ldloc_S, myLocalBuilder1 );
      myAdderIL->Emit( OpCodes::Ret );
      return myTypeBuilder->CreateType();
   }
};

int main()
{
   Type^ myAddType = ILGenerator_BeginFinallyBlock::AddType();
   Object^ myObject1 = Activator::CreateInstance( myAddType );
   array<Object^>^myObject2 = {15,15};
   myAddType->InvokeMember( "DoAdd", BindingFlags::InvokeMethod, nullptr, myObject1, myObject2 );
}

using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
using System.Security.Permissions;

public class ILGenerator_BeginFinallyBlock
{
   public static Type AddType()
   {
      // Create an assembly.
      AssemblyName myAssemblyName = new AssemblyName();
      myAssemblyName.Name = "AdderExceptionAsm";

      // Create dynamic assembly.
      AppDomain myAppDomain = Thread.GetDomain();
      AssemblyBuilder myAssemblyBuilder = myAppDomain.DefineDynamicAssembly(myAssemblyName,
         AssemblyBuilderAccess.Run);

      // Create a dynamic module.
      ModuleBuilder myModuleBuilder = myAssemblyBuilder.DefineDynamicModule("AdderExceptionMod");
      TypeBuilder myTypeBuilder = myModuleBuilder.DefineType("Adder");
      Type[] adderParams = new Type[] {typeof(int), typeof(int)};

      // Define method to add two numbers.
      MethodBuilder myMethodBuilder = myTypeBuilder.DefineMethod("DoAdd",MethodAttributes.Public |
         MethodAttributes.Static,typeof(int),adderParams);
      ILGenerator myAdderIL = myMethodBuilder.GetILGenerator();

      // Create constructor.
      ConstructorInfo myConstructorInfo = typeof(OverflowException).GetConstructor(
         new Type[]{typeof(string)});
      MethodInfo myExToStrMI = typeof(OverflowException).GetMethod("ToString");
      MethodInfo myWriteLineMI = typeof(Console).GetMethod("WriteLine",new Type[]
         {typeof(string),typeof(object)});

      // Declare local variable.
      LocalBuilder myLocalBuilder1 = myAdderIL.DeclareLocal(typeof(int));
      LocalBuilder myLocalBuilder2 = myAdderIL.DeclareLocal(typeof(OverflowException));

      // Define label.
      Label myFailedLabel = myAdderIL.DefineLabel();
      Label myEndOfMethodLabel = myAdderIL.DefineLabel();

      // Begin exception block.
      Label myLabel = myAdderIL.BeginExceptionBlock();

      myAdderIL.Emit(OpCodes.Ldarg_0);
      myAdderIL.Emit(OpCodes.Ldc_I4_S, 10);
      myAdderIL.Emit(OpCodes.Bgt_S, myFailedLabel);

      myAdderIL.Emit(OpCodes.Ldarg_1);
      myAdderIL.Emit(OpCodes.Ldc_I4_S, 10);
      myAdderIL.Emit(OpCodes.Bgt_S, myFailedLabel);

      myAdderIL.Emit(OpCodes.Ldarg_0);
      myAdderIL.Emit(OpCodes.Ldarg_1);
      myAdderIL.Emit(OpCodes.Add_Ovf_Un);
      myAdderIL.Emit(OpCodes.Stloc_S, myLocalBuilder1);
      myAdderIL.Emit(OpCodes.Br_S, myEndOfMethodLabel);

      myAdderIL.MarkLabel(myFailedLabel);
      myAdderIL.Emit(OpCodes.Ldstr, "Cannot accept values over 10 for add.");
      myAdderIL.Emit(OpCodes.Newobj, myConstructorInfo);

      myAdderIL.Emit(OpCodes.Stloc_S, myLocalBuilder2);
      myAdderIL.Emit(OpCodes.Ldloc_S, myLocalBuilder2);

      // Throw the exception.
      myAdderIL.ThrowException(typeof(OverflowException));

      // Call 'BeginExceptFilterBlock'.
      myAdderIL.BeginExceptFilterBlock();
      myAdderIL.EmitWriteLine("Except filter block called.");

      // Call catch block.
      myAdderIL.BeginCatchBlock(null);

      // Call other catch block.
      myAdderIL.BeginCatchBlock(typeof(OverflowException));

      myAdderIL.Emit(OpCodes.Ldstr, "{0}");
      myAdderIL.Emit(OpCodes.Ldloc_S, myLocalBuilder2);
      myAdderIL.EmitCall(OpCodes.Callvirt, myExToStrMI, null);
      myAdderIL.EmitCall(OpCodes.Call, myWriteLineMI, null);
      myAdderIL.Emit(OpCodes.Ldc_I4_M1);
      myAdderIL.Emit(OpCodes.Stloc_S, myLocalBuilder1);

      // Call finally block.
      myAdderIL.BeginFinallyBlock();
      myAdderIL.EmitWriteLine("Finally block called.");

      // End the exception block.
      myAdderIL.EndExceptionBlock();

      myAdderIL.MarkLabel(myEndOfMethodLabel);
      myAdderIL.Emit(OpCodes.Ldloc_S, myLocalBuilder1);
      myAdderIL.Emit(OpCodes.Ret);

      return myTypeBuilder.CreateType();
   }
   
   public static void Main()
   {
      Type myAddType = AddType();
      object myObject1 = Activator.CreateInstance(myAddType);
      object[] myObject2 = new object[]{15,15};
      myAddType.InvokeMember("DoAdd", BindingFlags.InvokeMethod,
         null, myObject1, myObject2);
   }
}

Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit
Imports System.Security.Permissions

Public Class ILGenerator_BeginFinallyBlock
   Public Shared Function AddType() As Type
      ' Create an assembly.
      Dim myAssemblyName As New AssemblyName()
      myAssemblyName.Name = "AdderExceptionAsm"

      ' Create dynamic assembly.
      Dim myAppDomain As AppDomain = Thread.GetDomain()
      Dim myAssemblyBuilder As AssemblyBuilder = _
            myAppDomain.DefineDynamicAssembly(myAssemblyName, AssemblyBuilderAccess.Run)

      ' Create a dynamic module.
      Dim myModuleBuilder As ModuleBuilder = _
            myAssemblyBuilder.DefineDynamicModule("AdderExceptionMod")
      Dim myTypeBuilder As TypeBuilder = myModuleBuilder.DefineType("Adder")
      Dim adderParams() As Type = {GetType(Integer), GetType(Integer)}

      ' Define method to add two numbers.
      Dim myMethodBuilder As MethodBuilder = _
            myTypeBuilder.DefineMethod("DoAdd", MethodAttributes.Public Or _
            MethodAttributes.Static, GetType(Integer), adderParams)
      Dim myAdderIL As ILGenerator = myMethodBuilder.GetILGenerator()

      ' Create constructor.
      Dim myConstructorInfo As ConstructorInfo = _
            GetType(OverflowException).GetConstructor(New Type() {GetType(String)})
      Dim myExToStrMI As MethodInfo = GetType(OverflowException).GetMethod("ToString")
      Dim myWriteLineMI As MethodInfo = _
            GetType(Console).GetMethod("WriteLine", New Type() {GetType(String), GetType(Object)})

      ' Declare local variable.
      Dim myLocalBuilder1 As LocalBuilder = myAdderIL.DeclareLocal(GetType(Integer))
      Dim myLocalBuilder2 As LocalBuilder = myAdderIL.DeclareLocal(GetType(OverflowException))

      ' Define label.
      Dim myFailedLabel As Label = myAdderIL.DefineLabel()
      Dim myEndOfMethodLabel As Label = myAdderIL.DefineLabel()

      ' Begin exception block.
      Dim myLabel As Label = myAdderIL.BeginExceptionBlock()

      myAdderIL.Emit(OpCodes.Ldarg_0)
      myAdderIL.Emit(OpCodes.Ldc_I4_S, 10)
      myAdderIL.Emit(OpCodes.Bgt_S, myFailedLabel)

      myAdderIL.Emit(OpCodes.Ldarg_1)
      myAdderIL.Emit(OpCodes.Ldc_I4_S, 10)
      myAdderIL.Emit(OpCodes.Bgt_S, myFailedLabel)

      myAdderIL.Emit(OpCodes.Ldarg_0)
      myAdderIL.Emit(OpCodes.Ldarg_1)
      myAdderIL.Emit(OpCodes.Add_Ovf_Un)
      myAdderIL.Emit(OpCodes.Stloc_S, myLocalBuilder1)
      myAdderIL.Emit(OpCodes.Br_S, myEndOfMethodLabel)

      myAdderIL.MarkLabel(myFailedLabel)
      myAdderIL.Emit(OpCodes.Ldstr, "Cannot accept values over 10 for add.")
      myAdderIL.Emit(OpCodes.Newobj, myConstructorInfo)

      myAdderIL.Emit(OpCodes.Stloc_S, myLocalBuilder2)
      myAdderIL.Emit(OpCodes.Ldloc_S, myLocalBuilder2)

      ' Throw the exception.
      myAdderIL.ThrowException(GetType(OverflowException))

      ' Call 'BeginExceptFilterBlock'.
      myAdderIL.BeginExceptFilterBlock()
      myAdderIL.EmitWriteLine("Except filter block called.")

      ' Call catch block.
      myAdderIL.BeginCatchBlock(Nothing)

      ' Call other catch block.
      myAdderIL.BeginCatchBlock(GetType(OverflowException))

      myAdderIL.Emit(OpCodes.Ldstr, "{0}")
      myAdderIL.Emit(OpCodes.Ldloc_S, myLocalBuilder2)
      myAdderIL.EmitCall(OpCodes.Callvirt, myExToStrMI, Nothing)
      myAdderIL.EmitCall(OpCodes.Call, myWriteLineMI, Nothing)
      myAdderIL.Emit(OpCodes.Ldc_I4_M1)
      myAdderIL.Emit(OpCodes.Stloc_S, myLocalBuilder1)

      ' Call finally block.
      myAdderIL.BeginFinallyBlock()
      myAdderIL.EmitWriteLine("Finally block called.")

      ' End the exception block.
      myAdderIL.EndExceptionBlock()

      myAdderIL.MarkLabel(myEndOfMethodLabel)
      myAdderIL.Emit(OpCodes.Ldloc_S, myLocalBuilder1)
      myAdderIL.Emit(OpCodes.Ret)

      Return myTypeBuilder.CreateType()
   End Function 'AddType

   <PermissionSetAttribute(SecurityAction.Demand, Name:="FullTrust")> _
   Public Shared Sub Main()
      Dim myAddType As Type = AddType()
      Dim myObject1 As Object = Activator.CreateInstance(myAddType)
      Dim myObject2() As Object = {15, 15}
      myAddType.InvokeMember("DoAdd", BindingFlags.InvokeMethod, Nothing, myObject1, myObject2)
   End Sub
End Class