Generic dynamic method using DefineMethod

This example illustrates how you can define a generic dynamic method and call it. In the sample below we define a method void HelloWorld<T>(T val) in type Hello and call it.


The body of the HelloWorld Method accesses the parameter passed to the method and prints it by calling WriteLine. I have created a module so that you can see the IL that is generated from this code.


using System;

using System.Collections.Generic;

using System.Text;

using System.Reflection.Emit;

using System.Reflection;


public interface IHelloWorld {

    void HelloWorld<T>(T val);


public class HelloClass {

    static void Main(string[] args) {

        AppDomain cd = System.Threading.Thread.GetDomain();

        AssemblyName an = new AssemblyName();

        an.Name = “HelloClass”;

        AssemblyBuilder ab = cd.DefineDynamicAssembly(an, AssemblyBuilderAccess.RunAndSave);

        ModuleBuilder mb = ab.DefineDynamicModule(“HelloModule”, “HelloModule.dll”, true);

        TypeBuilder tb = mb.DefineType(“Hello”, TypeAttributes.Class | TypeAttributes.Public);

        TypeBuilder ntb = tb.DefineNestedType(“NestedHello”,TypeAttributes.NestedPublic, typeof(HelloClass), new Type[] {typeof(IHelloWorld)});


        MethodBuilder meth = ntb.DefineMethod(“HelloWorld”, MethodAttributes.Public | MethodAttributes.Virtual, typeof(void), Type.EmptyTypes);

        string[] typeParamNames = {“T”};

        GenericTypeParameterBuilder[] typeParameters = meth.DefineGenericParameters(typeParamNames);

        Type[] parms = { typeParameters[0] };



        ILGenerator il = meth.GetILGenerator();

        MethodInfo infoMethod = typeof(Console).GetMethod(“WriteLine”, new Type[] { typeof(string) });

        if (infoMethod != null)



            il.Emit(OpCodes.Box, typeParameters[0]);

            il.Emit(OpCodes.Call, infoMethod);




        MethodInfo myHelloMethodInfo = typeof(IHelloWorld).GetMethod(“HelloWorld”);

        ntb.DefineMethodOverride(meth, myHelloMethodInfo);


        Type myType = tb.CreateType();

        Type myNestedClassType = ntb.CreateType();

        IHelloWorld ihw = (IHelloWorld)Activator.CreateInstance(myNestedClassType);

        ihw.HelloWorld(“Calling generic dynamic method”);





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