ConstructorBuilder.GetILGenerator Method

Definition

Gets an ILGenerator that can be used to emit a method body for this constructor.

Overloads

GetILGenerator(Int32)

Gets an ILGenerator object, with the specified MSIL stream size, that can be used to build a method body for this constructor.

GetILGenerator()

Gets an ILGenerator for this constructor.

GetILGenerator(Int32)

Gets an ILGenerator object, with the specified MSIL stream size, that can be used to build a method body for this constructor.

public:
 System::Reflection::Emit::ILGenerator ^ GetILGenerator(int streamSize);
public System.Reflection.Emit.ILGenerator GetILGenerator (int streamSize);
member this.GetILGenerator : int -> System.Reflection.Emit.ILGenerator
Public Function GetILGenerator (streamSize As Integer) As ILGenerator

Parameters

streamSize
Int32

The size of the MSIL stream, in bytes.

Returns

An ILGenerator for this constructor.

Exceptions

The constructor is a parameterless constructor.

-or-

The constructor has MethodAttributes or MethodImplAttributes flags indicating that it should not have a method body.

Remarks

The runtime generates the code for default constructors. Therefore, if an attempt is made to obtain an ILGenerator for a parameterless constructor, an exception is thrown.

GetILGenerator()

Gets an ILGenerator for this constructor.

public:
 System::Reflection::Emit::ILGenerator ^ GetILGenerator();
public System.Reflection.Emit.ILGenerator GetILGenerator ();
member this.GetILGenerator : unit -> System.Reflection.Emit.ILGenerator
Public Function GetILGenerator () As ILGenerator

Returns

An ILGenerator object for this constructor.

Exceptions

The constructor is a parameterless constructor.

-or-

The constructor has MethodAttributes or MethodImplAttributes flags indicating that it should not have a method body.

Examples

The following code sample illustrates the use of the GetILGenerator method.

using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
Type^ DynamicPointTypeGen()
{
   Type^ pointType = nullptr;
   array<Type^>^temp0 = {int::typeid,int::typeid,int::typeid};
   array<Type^>^ctorParams = temp0;
   AppDomain^ myDomain = Thread::GetDomain();
   AssemblyName^ myAsmName = gcnew AssemblyName;
   myAsmName->Name = "MyDynamicAssembly";
   AssemblyBuilder^ myAsmBuilder = myDomain->DefineDynamicAssembly( myAsmName, AssemblyBuilderAccess::RunAndSave );
   ModuleBuilder^ pointModule = myAsmBuilder->DefineDynamicModule( "PointModule", "Point.dll" );
   TypeBuilder^ pointTypeBld = pointModule->DefineType( "Point", TypeAttributes::Public );
   FieldBuilder^ xField = pointTypeBld->DefineField( "x", int::typeid, FieldAttributes::Public );
   FieldBuilder^ yField = pointTypeBld->DefineField( "y", int::typeid, FieldAttributes::Public );
   FieldBuilder^ zField = pointTypeBld->DefineField( "z", int::typeid, FieldAttributes::Public );
   Type^ objType = Type::GetType( "System.Object" );
   ConstructorInfo^ objCtor = objType->GetConstructor( gcnew array<Type^>(0) );
   ConstructorBuilder^ pointCtor = pointTypeBld->DefineConstructor( MethodAttributes::Public, CallingConventions::Standard, ctorParams );
   ILGenerator^ ctorIL = pointCtor->GetILGenerator();
   
   // NOTE: ldarg.0 holds the "this" reference - ldarg.1, ldarg.2, and ldarg.3
   // hold the actual passed parameters. ldarg.0 is used by instance methods
   // to hold a reference to the current calling bject instance. Static methods
   // do not use arg.0, since they are not instantiated and hence no reference
   // is needed to distinguish them.
   ctorIL->Emit( OpCodes::Ldarg_0 );
   
   // Here, we wish to create an instance of System::Object by invoking its
   // constructor, as specified above.
   ctorIL->Emit( OpCodes::Call, objCtor );
   
   // Now, we'll load the current instance in arg 0, along
   // with the value of parameter "x" stored in arg 1, into stfld.
   ctorIL->Emit( OpCodes::Ldarg_0 );
   ctorIL->Emit( OpCodes::Ldarg_1 );
   ctorIL->Emit( OpCodes::Stfld, xField );
   
   // Now, we store arg 2 "y" in the current instance with stfld.
   ctorIL->Emit( OpCodes::Ldarg_0 );
   ctorIL->Emit( OpCodes::Ldarg_2 );
   ctorIL->Emit( OpCodes::Stfld, yField );
   
   // Last of all, arg 3 "z" gets stored in the current instance.
   ctorIL->Emit( OpCodes::Ldarg_0 );
   ctorIL->Emit( OpCodes::Ldarg_3 );
   ctorIL->Emit( OpCodes::Stfld, zField );
   
   // Our work complete, we return.
   ctorIL->Emit( OpCodes::Ret );
   
   // Now, let's create three very simple methods so we can see our fields.
   array<String^>^temp1 = {"GetX","GetY","GetZ"};
   array<String^>^mthdNames = temp1;
   System::Collections::IEnumerator^ myEnum = mthdNames->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      String^ mthdName = safe_cast<String^>(myEnum->Current);
      MethodBuilder^ getFieldMthd = pointTypeBld->DefineMethod( mthdName, MethodAttributes::Public, int::typeid, nullptr );
      ILGenerator^ mthdIL = getFieldMthd->GetILGenerator();
      mthdIL->Emit( OpCodes::Ldarg_0 );
      if ( mthdName->Equals( "GetX" ) )
            mthdIL->Emit( OpCodes::Ldfld, xField );
      else
      if ( mthdName->Equals( "GetY" ) )
            mthdIL->Emit( OpCodes::Ldfld, yField );
      else
      if ( mthdName->Equals( "GetZ" ) )
            mthdIL->Emit( OpCodes::Ldfld, zField );



      mthdIL->Emit( OpCodes::Ret );
   }

   pointType = pointTypeBld->CreateType();
   
   // Let's save it, just for posterity.
   myAsmBuilder->Save( "Point.dll" );
   return pointType;
}

int main()
{
   Type^ myDynamicType = nullptr;
   Object^ aPoint = nullptr;
   array<Type^>^temp2 = {int::typeid,int::typeid,int::typeid};
   array<Type^>^aPtypes = temp2;
   array<Object^>^temp3 = {4,5,6};
   array<Object^>^aPargs = temp3;
   
   // Call the  method to build our dynamic class.
   myDynamicType = DynamicPointTypeGen();
   Console::WriteLine( "Some information about my new Type '{0}':", myDynamicType->FullName );
   Console::WriteLine( "Assembly: '{0}'", myDynamicType->Assembly );
   Console::WriteLine( "Attributes: '{0}'", myDynamicType->Attributes );
   Console::WriteLine( "Module: '{0}'", myDynamicType->Module );
   Console::WriteLine( "Members: " );
   System::Collections::IEnumerator^ myEnum = myDynamicType->GetMembers()->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      MemberInfo^ member = safe_cast<MemberInfo^>(myEnum->Current);
      Console::WriteLine( "-- {0} {1};", member->MemberType, member->Name );
   }

   Console::WriteLine( "---" );
   
   // Let's take a look at the constructor we created.
   ConstructorInfo^ myDTctor = myDynamicType->GetConstructor( aPtypes );
   Console::WriteLine( "Constructor: {0};", myDTctor );
   Console::WriteLine( "---" );
   
   // Now, we get to use our dynamically-created class by invoking the constructor.
   aPoint = myDTctor->Invoke( aPargs );
   Console::WriteLine( "aPoint is type {0}.", aPoint->GetType() );
   
   // Finally, let's reflect on the instance of our new type - aPoint - and
   // make sure everything proceeded according to plan.
   Console::WriteLine( "aPoint.x = {0}", myDynamicType->InvokeMember( "GetX", BindingFlags::InvokeMethod, nullptr, aPoint, gcnew array<Object^>(0) ) );
   Console::WriteLine( "aPoint.y = {0}", myDynamicType->InvokeMember( "GetY", BindingFlags::InvokeMethod, nullptr, aPoint, gcnew array<Object^>(0) ) );
   Console::WriteLine( "aPoint.z = {0}", myDynamicType->InvokeMember( "GetZ", BindingFlags::InvokeMethod, nullptr, aPoint, gcnew array<Object^>(0) ) );
   
   // +++ OUTPUT +++
   // Some information about my new Type 'Point':
   // Assembly: 'MyDynamicAssembly, Version=0.0.0.0'
   // Attributes: 'AutoLayout, AnsiClass, NotPublic, Public'
   // Module: 'PointModule'
   // Members:
   // -- Field x;
   // -- Field y;
   // -- Field z;
   // -- Method GetHashCode;
   // -- Method Equals;
   // -- Method ToString;
   // -- Method GetType;
   // -- Constructor .ctor;
   // ---
   // Constructor: Void .ctor(Int32, Int32, Int32);
   // ---
   // aPoint is type Point.
   // aPoint.x = 4
   // aPoint.y = 5
   // aPoint.z = 6
}


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

class TestCtorBuilder {
 
    public static Type DynamicPointTypeGen() {
      
       Type pointType = null;
       Type[] ctorParams = new Type[] {typeof(int),
                        typeof(int),
                        typeof(int)};
    
       AppDomain myDomain = Thread.GetDomain();
       AssemblyName myAsmName = new AssemblyName();
       myAsmName.Name = "MyDynamicAssembly";
    
       AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
                      myAsmName, 
                      AssemblyBuilderAccess.RunAndSave);

       ModuleBuilder pointModule = myAsmBuilder.DefineDynamicModule("PointModule",
                                    "Point.dll");

       TypeBuilder pointTypeBld = pointModule.DefineType("Point",
                                      TypeAttributes.Public);

       FieldBuilder xField = pointTypeBld.DefineField("x", typeof(int),
                                                          FieldAttributes.Public);
       FieldBuilder yField = pointTypeBld.DefineField("y", typeof(int), 
                                                          FieldAttributes.Public);
       FieldBuilder zField = pointTypeBld.DefineField("z", typeof(int),
                                                          FieldAttributes.Public);


           Type objType = Type.GetType("System.Object"); 
           ConstructorInfo objCtor = objType.GetConstructor(new Type[0]);

       ConstructorBuilder pointCtor = pointTypeBld.DefineConstructor(
                      MethodAttributes.Public,
                      CallingConventions.Standard,
                      ctorParams);
       ILGenerator ctorIL = pointCtor.GetILGenerator();

       // NOTE: ldarg.0 holds the "this" reference - ldarg.1, ldarg.2, and ldarg.3
       // hold the actual passed parameters. ldarg.0 is used by instance methods
       // to hold a reference to the current calling object instance. Static methods
       // do not use arg.0, since they are not instantiated and hence no reference
       // is needed to distinguish them. 

           ctorIL.Emit(OpCodes.Ldarg_0);

       // Here, we wish to create an instance of System.Object by invoking its
       // constructor, as specified above.

           ctorIL.Emit(OpCodes.Call, objCtor);

       // Now, we'll load the current instance ref in arg 0, along
       // with the value of parameter "x" stored in arg 1, into stfld.

           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_1);
           ctorIL.Emit(OpCodes.Stfld, xField); 

       // Now, we store arg 2 "y" in the current instance with stfld.

           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_2);
           ctorIL.Emit(OpCodes.Stfld, yField); 

       // Last of all, arg 3 "z" gets stored in the current instance.

           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_3);
           ctorIL.Emit(OpCodes.Stfld, zField); 
           
           // Our work complete, we return.

       ctorIL.Emit(OpCodes.Ret); 

       // Now, let's create three very simple methods so we can see our fields.

       string[] mthdNames = new string[] {"GetX", "GetY", "GetZ"}; 

           foreach (string mthdName in mthdNames) {
              MethodBuilder getFieldMthd = pointTypeBld.DefineMethod(
                           mthdName, 
                           MethodAttributes.Public,
                                           typeof(int), 
                                           null);
          ILGenerator mthdIL = getFieldMthd.GetILGenerator();
       
          mthdIL.Emit(OpCodes.Ldarg_0);
          switch (mthdName) {
             case "GetX": mthdIL.Emit(OpCodes.Ldfld, xField);
                  break;
             case "GetY": mthdIL.Emit(OpCodes.Ldfld, yField);
                  break;
             case "GetZ": mthdIL.Emit(OpCodes.Ldfld, zField);
                  break;

          }
          mthdIL.Emit(OpCodes.Ret);

           }
       // Finally, we create the type.

       pointType = pointTypeBld.CreateType();

       // Let's save it, just for posterity.
       
       myAsmBuilder.Save("Point.dll");
    
       return pointType;

    }

    public static void Main() {
    
       Type myDynamicType = null;
           object aPoint = null;
       Type[] aPtypes = new Type[] {typeof(int), typeof(int), typeof(int)};
           object[] aPargs = new object[] {4, 5, 6};
    
       // Call the  method to build our dynamic class.

       myDynamicType = DynamicPointTypeGen();

       Console.WriteLine("Some information about my new Type '{0}':",
                  myDynamicType.FullName);
       Console.WriteLine("Assembly: '{0}'", myDynamicType.Assembly);
       Console.WriteLine("Attributes: '{0}'", myDynamicType.Attributes);
       Console.WriteLine("Module: '{0}'", myDynamicType.Module);
       Console.WriteLine("Members: "); 
       foreach (MemberInfo member in myDynamicType.GetMembers()) {
        Console.WriteLine("-- {0} {1};", member.MemberType, member.Name);
       }

           Console.WriteLine("---");

       // Let's take a look at the constructor we created.

       ConstructorInfo myDTctor = myDynamicType.GetConstructor(aPtypes);
           Console.WriteLine("Constructor: {0};", myDTctor.ToString());

           Console.WriteLine("---");
      
           // Now, we get to use our dynamically-created class by invoking the constructor. 

       aPoint = myDTctor.Invoke(aPargs);
           Console.WriteLine("aPoint is type {0}.", aPoint.GetType());
           

       // Finally, let's reflect on the instance of our new type - aPoint - and
       // make sure everything proceeded according to plan.

       Console.WriteLine("aPoint.x = {0}",
                 myDynamicType.InvokeMember("GetX",
                                BindingFlags.InvokeMethod,
                            null,
                            aPoint,
                            new object[0]));
       Console.WriteLine("aPoint.y = {0}",
                 myDynamicType.InvokeMember("GetY",
                                BindingFlags.InvokeMethod,
                            null,
                            aPoint,
                            new object[0]));
       Console.WriteLine("aPoint.z = {0}",
                 myDynamicType.InvokeMember("GetZ",
                                BindingFlags.InvokeMethod,
                            null,
                            aPoint,
                            new object[0]));

        

       // +++ OUTPUT +++
       // Some information about my new Type 'Point':
       // Assembly: 'MyDynamicAssembly, Version=0.0.0.0'
       // Attributes: 'AutoLayout, AnsiClass, NotPublic, Public'
       // Module: 'PointModule'
       // Members: 
       // -- Field x;
       // -- Field y;
       // -- Field z;
           // -- Method GetHashCode;
           // -- Method Equals;
           // -- Method ToString;
           // -- Method GetType;
           // -- Constructor .ctor;
       // ---
       // Constructor: Void .ctor(Int32, Int32, Int32);
       // ---
       // aPoint is type Point.
       // aPoint.x = 4
       // aPoint.y = 5
       // aPoint.z = 6
        
    }
    
}


Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit

 _

Class TestCtorBuilder
   
   
   Public Shared Function DynamicPointTypeGen() As Type
      
      Dim pointType As Type = Nothing
      Dim ctorParams() As Type = {GetType(Integer), GetType(Integer), GetType(Integer)}
      
      Dim myDomain As AppDomain = Thread.GetDomain()
      Dim myAsmName As New AssemblyName()
      myAsmName.Name = "MyDynamicAssembly"
      
      Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess.RunAndSave)
      
      Dim pointModule As ModuleBuilder = myAsmBuilder.DefineDynamicModule("PointModule", "Point.dll")
      
      Dim pointTypeBld As TypeBuilder = pointModule.DefineType("Point", TypeAttributes.Public)
      
      Dim xField As FieldBuilder = pointTypeBld.DefineField("x", GetType(Integer), FieldAttributes.Public)
      Dim yField As FieldBuilder = pointTypeBld.DefineField("y", GetType(Integer), FieldAttributes.Public)
      Dim zField As FieldBuilder = pointTypeBld.DefineField("z", GetType(Integer), FieldAttributes.Public)
      
      Dim objType As Type = Type.GetType("System.Object")
      Dim objCtor As ConstructorInfo = objType.GetConstructor(New Type() {})
      
      Dim pointCtor As ConstructorBuilder = pointTypeBld.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, ctorParams)
      Dim ctorIL As ILGenerator = pointCtor.GetILGenerator()
      
      ' NOTE: ldarg.0 holds the "this" reference - ldarg.1, ldarg.2, and ldarg.3
      ' hold the actual passed parameters. ldarg.0 is used by instance methods
      ' to hold a reference to the current calling object instance. Static methods
      ' do not use arg.0, since they are not instantiated and hence no reference
      ' is needed to distinguish them. 
      ctorIL.Emit(OpCodes.Ldarg_0)
      
      ' Here, we wish to create an instance of System.Object by invoking its
      ' constructor, as specified above.
      ctorIL.Emit(OpCodes.Call, objCtor)
      
      ' Now, we'll load the current instance ref in arg 0, along
      ' with the value of parameter "x" stored in arg 1, into stfld.
      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Ldarg_1)
      ctorIL.Emit(OpCodes.Stfld, xField)
      
      ' Now, we store arg 2 "y" in the current instance with stfld.
      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Ldarg_2)
      ctorIL.Emit(OpCodes.Stfld, yField)
      
      ' Last of all, arg 3 "z" gets stored in the current instance.
      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Ldarg_3)
      ctorIL.Emit(OpCodes.Stfld, zField)
      
      ' Our work complete, we return.
      ctorIL.Emit(OpCodes.Ret)
      
      ' Now, let's create three very simple methods so we can see our fields.
      Dim mthdNames() As String = {"GetX", "GetY", "GetZ"}
      
      Dim mthdName As String
      For Each mthdName In  mthdNames
         Dim getFieldMthd As MethodBuilder = pointTypeBld.DefineMethod(mthdName, MethodAttributes.Public, GetType(Integer), Nothing)
         Dim mthdIL As ILGenerator = getFieldMthd.GetILGenerator()
         
         mthdIL.Emit(OpCodes.Ldarg_0)
         Select Case mthdName
            Case "GetX"
               mthdIL.Emit(OpCodes.Ldfld, xField)
            Case "GetY"
               mthdIL.Emit(OpCodes.Ldfld, yField)
            Case "GetZ"
               mthdIL.Emit(OpCodes.Ldfld, zField)
         End Select
         
         mthdIL.Emit(OpCodes.Ret)
      Next mthdName 
      ' Finally, we create the type.
      pointType = pointTypeBld.CreateType()
      
      ' Let's save it, just for posterity.
      myAsmBuilder.Save("Point.dll")
      
      Return pointType
   End Function 'DynamicPointTypeGen
    
   
   Public Shared Sub Main()
      
      Dim myDynamicType As Type = Nothing
      Dim aPoint As Object = Nothing
      Dim aPtypes() As Type = {GetType(Integer), GetType(Integer), GetType(Integer)}
      Dim aPargs() As Object = {4, 5, 6}
      
      ' Call the  method to build our dynamic class.
      myDynamicType = DynamicPointTypeGen()
      
      Console.WriteLine("Some information about my new Type '{0}':", myDynamicType.FullName)
      Console.WriteLine("Assembly: '{0}'", myDynamicType.Assembly)
      Console.WriteLine("Attributes: '{0}'", myDynamicType.Attributes)
      Console.WriteLine("Module: '{0}'", myDynamicType.Module)
      Console.WriteLine("Members: ")
      Dim member As MemberInfo
      For Each member In  myDynamicType.GetMembers()
         Console.WriteLine("-- {0} {1};", member.MemberType, member.Name)
      Next member
      
      Console.WriteLine("---")
      
      ' Let's take a look at the constructor we created.
      Dim myDTctor As ConstructorInfo = myDynamicType.GetConstructor(aPtypes)
      Console.WriteLine("Constructor: {0};", myDTctor.ToString())
      
      Console.WriteLine("---")
      
      ' Now, we get to use our dynamically-created class by invoking the constructor. 
      aPoint = myDTctor.Invoke(aPargs)
      Console.WriteLine("aPoint is type {0}.", aPoint.GetType())
      
      
      ' Finally, let's reflect on the instance of our new type - aPoint - and
      ' make sure everything proceeded according to plan.
      Console.WriteLine("aPoint.x = {0}", myDynamicType.InvokeMember("GetX", BindingFlags.InvokeMethod, Nothing, aPoint, New Object() {}))
      Console.WriteLine("aPoint.y = {0}", myDynamicType.InvokeMember("GetY", BindingFlags.InvokeMethod, Nothing, aPoint, New Object() {}))
      Console.WriteLine("aPoint.z = {0}", myDynamicType.InvokeMember("GetZ", BindingFlags.InvokeMethod, Nothing, aPoint, New Object() {}))
   End Sub
End Class



' +++ OUTPUT +++
' Some information about my new Type 'Point':
' Assembly: 'MyDynamicAssembly, Version=0.0.0.0'
' Attributes: 'AutoLayout, AnsiClass, NotPublic, Public'
' Module: 'PointModule'
' Members: 
' -- Field x;
' -- Field y;
' -- Field z;
' -- Method GetHashCode;
' -- Method Equals;
' -- Method ToString;
' -- Method GetType;
' -- Constructor .ctor;
' ---
' Constructor: Void .ctor(Int32, Int32, Int32);
' ---
' aPoint is type Point.
' aPoint.x = 4
' aPoint.y = 5
' aPoint.z = 6

Remarks

The runtime generates the code for default constructors. Therefore, if an attempt is made to obtain an ILGenerator, an exception will be thrown.

Applies to