A script to create a dynamic subtype of a given type and overrides all virtual properties. Can be extended to raise events, call logging methods, etc...

DynamicProxyGeneration.csx

using System.Linq;
using System.Reflection.Emit;
using System.Reflection;
using static System.Console;

public T CreateProxy<T>() where T : class
{
    var baseType = typeof(T);

    var assemblyName = new AssemblyName("Poxies");
    var assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.RunAndSave);
    var moduleBuilder = assemblyBuilder.DefineDynamicModule($"{assemblyName.Name}.dll");

    string dynamicTypeName = Assembly.CreateQualifiedName(assemblyName.FullName, $"{baseType.Name}_Proxy");

    var typeBuilder = moduleBuilder.DefineType(dynamicTypeName, TypeAttributes.Public | TypeAttributes.Class, baseType);

    var getSetAttributes = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig | MethodAttributes.Virtual;
    var propertiesToOverride = baseType.GetProperties()
        .Where(p => p.GetGetMethod().IsVirtual)
        .ToArray();

    foreach (var p in propertiesToOverride)
    {
        var propertyBuilder = typeBuilder.DefineProperty(p.Name, PropertyAttributes.None, CallingConventions.HasThis, p.PropertyType, Type.EmptyTypes);

        var getMethod = typeBuilder.DefineMethod($"get_{p.Name}", getSetAttributes, p.PropertyType, Type.EmptyTypes);
        var getIlGenerator = getMethod.GetILGenerator();
        getIlGenerator.Emit(OpCodes.Ldarg_0);
        getIlGenerator.Emit(OpCodes.Call, p.GetGetMethod());
        getIlGenerator.Emit(OpCodes.Ret);

        var setMethod = typeBuilder.DefineMethod($"set_{p.Name}", getSetAttributes, null, new[] { p.PropertyType });
        var setIlGenerator = setMethod.GetILGenerator();
        setIlGenerator.Emit(OpCodes.Ldarg_0);
        setIlGenerator.Emit(OpCodes.Ldarg_1);
        setIlGenerator.Emit(OpCodes.Call, p.GetSetMethod());
        setIlGenerator.Emit(OpCodes.Nop);
        setIlGenerator.Emit(OpCodes.Ret);

        propertyBuilder.SetGetMethod(getMethod);
        propertyBuilder.SetSetMethod(setMethod);
    }

    var proxyType = typeBuilder.CreateType();
    // WriteLine($"AssemblyName: {assemblyName.Name}");
    // assemblyBuilder.Save($"{assemblyName.Name}.dll");
    return (T)Activator.CreateInstance(proxyType);
}

class BaseType
{
    public virtual int Id { get; set; }
    public virtual string Name { get; set; }
}

var t = CreateProxy<BaseType>();
t.Id = 5;
t.Name = "Hallo";
WriteLine(t.Id);
WriteLine(t.Name);

var type = t.GetType();
var properties = type
    .GetProperties()
    .Select(p => (getter: p.GetGetMethod(), setters: p.GetSetMethod()))
    .ToArray();