DynamicMethod.CreateDelegate Method (Type) (System.Reflection.Emit)

Imports System
Imports System.Reflection
Imports System.Reflection.Emit
Imports Microsoft.VisualBasic

Public Class Test
    ' Declare a delegate that will be used to execute the completed
    ' dynamic method. 
    Private Delegate Function HelloInvoker(ByVal msg As String, _
        ByVal ret As Integer) As Integer

    Public Shared Sub Main()
        ' 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 helloArgs() As Type = {GetType(String), GetType(Integer)}

        ' Create a dynamic method with the name "Hello", a return type
        ' of Integer, and two parameters whose types are specified by
        ' the array helloArgs. Create the method in the module that
        ' defines the Test class.
        Dim hello As New DynamicMethod("Hello", _
            GetType(Integer), _
            helloArgs, _
            GetType(Test).Module)

        ' Create an array that specifies the parameter types of the
        ' overload of Console.WriteLine to be used in Hello.
        Dim writeStringArgs() As Type = {GetType(String)}
        ' Get the overload of Console.WriteLine that has one
        ' String parameter.
        Dim writeString As MethodInfo = GetType(Console). _
            GetMethod("WriteLine", writeStringArgs) 

        ' Get an ILGenerator and emit a body for the dynamic method.
        Dim il As ILGenerator = hello.GetILGenerator()
        ' Load the first argument, which is a string, onto the stack.
        il.Emit(OpCodes.Ldarg_0)
        ' Call the overload of Console.WriteLine that prints a string.
        il.EmitCall(OpCodes.Call, writeString, Nothing)
        ' The Hello method returns the value of the second argument;
        ' to do this, load the onto the stack and return.
        il.Emit(OpCodes.Ldarg_1)
        il.Emit(OpCodes.Ret)

        ' Create a delegate that represents the dynamic method. This
        ' action completes the method, and any further attempts to
        ' change the method will cause an exception.
	Dim hi As HelloInvoker = _
            hello.CreateDelegate(GetType(HelloInvoker))

        ' Use the delegate to execute the dynamic method. Save and
        ' print the return value.
        Dim retval As Integer = hi(vbCrLf & "Hello, World!", 42)
        Console.WriteLine("Executing delegate hi(""Hello, World!"", 42) returned " _
            & retval)

        ' Do it again, with different arguments.
        retval = hi(vbCrLf & "Hi, Mom!", 5280)
        Console.WriteLine("Executing delegate hi(""Hi, Mom!"", 5280) returned " _
            & retval)

        ' Create an array of arguments to use with the Invoke method.
        Dim invokeArgs() As Object = {vbCrLf & "Hello, World!", 42}
        ' Invoke the dynamic method using the arguments. This is much
        ' slower than using the delegate, because you must create an
        ' array to contain the arguments, and ValueType arguments
        ' must be boxed. Note that this overload of Invoke is 
        ' inherited from MethodBase, and simply calls the more 
        ' complete overload of Invoke.
        Dim objRet As Object = hello.Invoke(Nothing, invokeArgs)
        Console.WriteLine("hello.Invoke returned " & objRet)
    End Sub
End Class

' This code example produces the following output:
'
'Hello, World!
'Executing delegate hi("Hello, World!", 42) returned 42
'
'Hi, Mom!
'Executing delegate hi("Hi, Mom!", 5280) returned 5280
'
'Hello, World!
'hello.Invoke returned 42
'

using System;
using System.Reflection;
using System.Reflection.Emit;
using Microsoft.VisualBasic;

public class Test
{
    // Declare a delegate that will be used to execute the completed
    // dynamic method. 
    private delegate int HelloInvoker(string msg, int ret);

    public static void Main()
    {
        // Create an array that specifies the types of the parameters
        // of the dynamic method. This method has a string parameter
        // and an int parameter.
        Type[] helloArgs = {typeof(string), typeof(int)};

        // Create a dynamic method with the name "Hello", a return type
        // of int, and two parameters whose types are specified by the
        // array helloArgs. Create the method in the module that
        // defines the Test class.
        DynamicMethod hello = new DynamicMethod("Hello", 
            typeof(int), 
            helloArgs, 
            typeof(Test).Module);

        // Create an array that specifies the parameter types of the
        // overload of Console.WriteLine to be used in Hello.
        Type[] writeStringArgs = {typeof(string)};
        // Get the overload of Console.WriteLine that has one
        // String parameter.
        MethodInfo writeString = 
            typeof(Console).GetMethod("WriteLine", writeStringArgs);

        // Get an ILGenerator and emit a body for the dynamic method.
        ILGenerator il = hello.GetILGenerator();
        // Load the first argument, which is a string, onto the stack.
        il.Emit(OpCodes.Ldarg_0);
        // Call the overload of Console.WriteLine that prints a string.
        il.EmitCall(OpCodes.Call, writeString, null);
        // The Hello method returns the value of the second argument;
        // to do this, load the onto the stack and return.
        il.Emit(OpCodes.Ldarg_1);
        il.Emit(OpCodes.Ret);

        // Create a delegate that represents the dynamic method. This
        // action completes the method, and any further attempts to
        // change the method will cause an exception.
        HelloInvoker hi = 
            (HelloInvoker) hello.CreateDelegate(typeof(HelloInvoker));

        // Use the delegate to execute the dynamic method. Save and
        // print the return value.
        int retval = hi("\r\nHello, World!", 42);
        Console.WriteLine("Executing delegate hi(\"Hello, World!\", 42) returned {0}",
            retval);

        // Do it again, with different arguments.
        retval = hi("\r\nHi, Mom!", 5280);
        Console.WriteLine("Executing delegate hi(\"Hi, Mom!\", 5280) returned {0}",
            retval);

        // Create an array of arguments to use with the Invoke method.
        object[] invokeArgs = {"\r\nHello, World!", 42};
        // Invoke the dynamic method using the arguments. This is much
        // slower than using the delegate, because you must create an
        // array to contain the arguments, and ValueType arguments
        // must be boxed.
        object objRet = hello.Invoke(null, invokeArgs);
        Console.WriteLine("hello.Invoke returned {0}", objRet);
    }
}

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

public ref class Test
{   
};

// Declare a delegate that will be used to execute the completed
// dynamic method.
delegate int HelloInvoker(String^ msg, int ret);

int main()
{
    // Create an array that specifies the types of the parameters
    // of the dynamic method. This method has a string parameter
    // and an int parameter.
    array<Type^>^ helloArgs = {String::typeid, int::typeid};

    // Create a dynamic method with the name "Hello", a return type
    // of int, and two parameters whose types are specified by the
    // array helloArgs. Create the method in the module that
    // defines the Test class.
    DynamicMethod^ hello = gcnew DynamicMethod("Hello", 
        int::typeid,
        helloArgs,
        Test::typeid->Module);

    // Create an array that specifies the parameter types of the
    // overload of Console.WriteLine to be used in Hello.
    array<Type^>^ writeStringArgs = {String::typeid};
    // Get the overload of Console.WriteLine that has one
    // String parameter.
    MethodInfo^ writeString =
        Console::typeid->GetMethod("WriteLine", writeStringArgs);

    // Get an ILGenerator and emit a body for the dynamic method.
    ILGenerator^ ilgen = hello->GetILGenerator();
    // Load the first argument, which is a string, onto the stack.
    ilgen->Emit(OpCodes::Ldarg_0);
    // Call the overload of Console.WriteLine that prints a string.
    ilgen->EmitCall(OpCodes::Call, writeString, nullptr);
    // The Hello method returns the value of the second argument;
    // to do this, load the onto the stack and return.
    ilgen->Emit(OpCodes::Ldarg_1);
    ilgen->Emit(OpCodes::Ret);

    // Create a delegate that represents the dynamic method. This
    // action completes the method, and any further attempts to
    // change the method will cause an exception.
    HelloInvoker^ helloDelegate =
        (HelloInvoker^) hello->CreateDelegate(HelloInvoker::typeid);

    // Use the delegate to execute the dynamic method. Save and
    // print the return value.
    int returnValue = helloDelegate("\r\nHello, World!", 42);
    Console::WriteLine("helloDelegate(\"Hello, World!\", 42) returned {0}",
        returnValue);

    // Do it again, with different arguments.
    returnValue = helloDelegate("\r\nHi, Mom!", 5280);
    Console::WriteLine("helloDelegate(\"Hi, Mom!\", 5280) returned {0}",
        returnValue);

    // Create an array of arguments to use with the Invoke method.
    array<Object^>^ delegateArgs = {"\r\nHello, World!", 42};
    // Invoke the dynamic method using the arguments. This is much
    // slower than using the delegate, because you must create an
    // array to contain the arguments, and ValueType arguments
    // must be boxed.
    Object^ returnValueObject = hello->Invoke(nullptr, delegateArgs);
    Console::WriteLine("hello.Invoke returned {0}", returnValueObject);
}