SaveAs options

I create several histogram and I save them as macro file (I do not precise any extension). I would like to know if it is possible to save them as macro file but with the extension .root?
Indeed, I need to have a file name with this forme myfile.root but myfile.root is a macro file. Actually, I create my files without extension and I rename them after …

I do not understand why you want to do that. It is very confusing. Anyhow it is not possible.