in reply to Re^3: Twisted sort requirements
in thread Twisted sort requirements

Um, I think the problem here is: if you don't know the author of "THIS BOOK FIRST" before the sorting begins, then you effectively end up changing the sort conditions in the middle of the sorting process, which would tend to make that process somewhat unstable at best.

I'll confess that I've forgotten most of the (relatively few) details I've ever known about sorting implementations, but I have a strong hunch that changing the sort criteria upon seeing input item N (where N is something other than "the first") would violate an essential underlying assumption that is built into most sort algorithms.