DynamicMethod.GetILGenerator Method

Return Value

Type: System.Reflection.Emit.ILGenerator
An ILGenerator object for the method.

Imports System.Reflection.Emit
Imports System.Reflection

Public Class Example

   ' Declare a delegate that can be used to execute the dynamic method.
   Private Delegate Function Caller(ByVal msg As String, _
        ByVal number As Integer) As String

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      ' Create an array that specifies the types of the parameters
      ' of the dynamic method. This method has a String parameter
      ' and an Integer parameter.
      Dim paramTypes() As Type = { GetType(String), GetType(Integer) }

      ' Create an unnamed dynamic method with a return type of
      ' Integer and with two parameters whose types are specified by
      ' the array paramTypes. The dynamic method is anonymously
      ' hosted. 
      Dim method As New DynamicMethod("", GetType(String), paramTypes)

      ' Get a MethodInfo for the overload of String.Format that
      ' takes a format string and an object for insertion in the format 
      ' string. The dynamic method uses this overload to format the 
      ' return string.
      Dim stringFormat As MethodInfo = GetType(String). _
          GetMethod("Format", New Type() { GetType(String), GetType(Object) })

      ' Get an ILGenerator and emit a body for the dynamic method.
      Dim il As ILGenerator = method.GetILGenerator()

      ' Load the arguments onto the execution stack. The second 
      ' argument is an Integer, so it must be boxed before it can be 
      ' passed to a parameter of type Object. 
      il.Emit(OpCodes.Ldarg_0)
      il.Emit(OpCodes.Ldarg_1)
      il.Emit(OpCodes.Box, GetType(Integer))

      ' Call the String.Format method. The return value from that call 
      ' is placed on the execution stack, so the dynamic method simply 
      ' returns.         
      il.Emit(OpCodes.Call, stringFormat)
      il.Emit(OpCodes.Ret)

      ' Create a delegate that represents the dynamic method. This
      ' action completes the dynamic method, and any further attempts
      ' to change the method have no effect.
      Dim callMethod As Caller = method.CreateDelegate(GetType(Caller))

      ' Invoke the delegate and display the result.
      Dim ret As String = callMethod("The second argument is: {0}.", 1969)

      outputBlock.Text &= _
         String.Format("Invoking the delegate returned the string '{0}'.", ret)

   End Sub

End Class

' This code example produces the following output:
'
'Invoking the delegate returned the string 'The second argument is: 1969.'.

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

public class Example
{
   // Declare a delegate that can be used to execute the dynamic method.
   private delegate string Caller(string msg, int number);

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // Create an array that specifies the types of the parameters
      // of the dynamic method. This method has a String parameter
      // and an Integer parameter.
      Type[] paramTypes = { typeof(string), typeof(int) };

      // Create an unnamed dynamic method with a return type of
      // Integer and with two parameters whose types are specified by
      // the array paramTypes. The dynamic method is anonymously
      // hosted. 
      DynamicMethod method = new DynamicMethod("", typeof(string), paramTypes);

      // Get a MethodInfo for the overload of String.Format that
      // takes a format string and an object for insertion in the format 
      // string. The dynamic method uses this overload to format the 
      // return string.
      MethodInfo stringFormat = typeof(string).GetMethod("Format", 
         new Type[] { typeof(string), typeof(object) });

      // Get an ILGenerator and emit a body for the dynamic method.
      ILGenerator il = method.GetILGenerator();

      // Load the arguments onto the execution stack. The second 
      // argument is an Integer, so it must be boxed before it can be 
      // passed to a parameter of type Object. 
      il.Emit(OpCodes.Ldarg_0);
      il.Emit(OpCodes.Ldarg_1);
      il.Emit(OpCodes.Box, typeof(int));

      // Call the String.Format method. The return value from that call 
      // is placed on the execution stack, so the dynamic method simply 
      // returns.         
      il.Emit(OpCodes.Call, stringFormat);
      il.Emit(OpCodes.Ret);

      // Create a delegate that represents the dynamic method. This
      // action completes the dynamic method, and any further attempts
      // to change the method have no effect.
      Caller callMethod = (Caller) method.CreateDelegate(typeof(Caller));

      // Invoke the delegate and display the result.
      string ret = callMethod("The second argument is: {0}.", 1969);

      outputBlock.Text += 
         String.Format("Invoking the delegate returned the string '{0}'.", ret);
   }
}

/* This code example produces the following output:

Invoking the delegate returned the string 'The second argument is: 1969.'.
 */