Android - How is the gen folder generated?

I created a program that uses a base project to generate other projects. The applications have the same functionalities, what changes is the layout, the images, the names of the packages, etc. The problem is that when I generate a new project, I open it in eclipse and give a 'clean' package where the file R is still with the same name as the base project, instead of the name of the new project, which obviously results in an error compilation. I thought that by clearing the project the package name in the gen folder would be changed to the same package name in the src folder. Can anyone tell me where the meta-information is extracted for the generation of the gen folder?