I can't really see a reason why source files should only be logic. For a long time we've operated on the principle that they ought to be readable too, because h

I can't really see a reason why source files should only be logic. For a long time we've operated on the principle that they ought to be readable too, because humans write them. So there are comments, formatting, and styles of programming to make what you're doing readable to others, like choice of variable names. Decide on a "stylesheet" to use with the people with whom you're working with, and try to stick to it. In a way tabs are an invitation to style them how you want.