GerandoCodigoEmExecucao

Program.cs

using System;
using System.Reflection.Emit;

namespace GerandoCodigoEmExecucao
{
    class Program
    {
        static void Main(string[] args)
        {
            Func<int, int, int> soma = Soma;
            Func<int, int, int> somaDinamico = CriaMetodoSomador();

            Console.WriteLine(soma(1,2));
            Console.WriteLine(somaDinamico(1,2));

            var typeVoid = typeof(void);
            var typeString = typeof(string);
            var dynamicMethod = new DynamicMethod("Print", typeVoid, new[] { typeString });

            var writeLine = typeof (Console).GetMethod("WriteLine", new[] {typeString});

            var ilGenerator = dynamicMethod.GetILGenerator();
            ilGenerator.Emit(OpCodes.Ldarg_0);
            ilGenerator.Emit(OpCodes.Call, writeLine);
            ilGenerator.Emit(OpCodes.Ret);
            
            dynamicMethod.Invoke(null, new[] {"Ola mundo!"});
        }

        static Func<int, int, int> CriaMetodoSomador()
        {
            var typeInt = typeof(int);
            var dynamicMethod = new DynamicMethod("SomaValores", typeInt, new[] { typeInt, typeInt });
            
            var ilGenerator = dynamicMethod.GetILGenerator();
            ilGenerator.Emit(OpCodes.Ldarg_0);
            ilGenerator.Emit(OpCodes.Ldarg_1);
            ilGenerator.Emit(OpCodes.Add);
            ilGenerator.Emit(OpCodes.Ret);

            var assinatura = typeof(Func<int,int,int>);

            return (Func<int, int, int>)dynamicMethod.CreateDelegate(assinatura);
        }

        static int Soma(int valorA, int valorB)
        {
            return valorA + valorB;
        }
    }
}