I'm not sure I get what you're saying. Are you asking if, once an application has been built, you can remove some of the code used to create it at runtime? Because you definately cannot do that. If you want to like, make a class behave differently or something, you might want to look into using dlls and rename a couple of dlls to use different implementation of the same functions, but you would still need to restart the application. If I understand you correctly, you should post specifically what you are trying to accomplish because there has to be a better way of doing it.