On Wed 13 Mar 2013 19:10, Mark H Weaver <m...@netris.org> writes: > Andy Wingo <wi...@pobox.com> writes: > >> On Wed 13 Mar 2013 14:09, "David A. Wheeler" <dwhee...@dwheeler.com> writes: >> >>> Andy Wingo: >>> >>>> So, we are repeating ourselves here :) I agree with you but I can't see >>>> a good way of implementing this. >>> >>> Would the per-port reader options be reasonable place to store the info >>> about EOF? >> >> For your own purposes that would be fine. But it cannot affect >> read-char / peek-char / etc for everyone, because it would have bad >> global effects on performance and correctness. That's why I'm pushing >> back on fixing this in Guile itself. > > I don't know, it might not be that bad, now that we've agreed on a way > to extend the port structure in 2.0. Maybe we could just have a "last > peek-char returned EOF" flag that would be consulted by the other read > primitives. > > I agree that we should not allow EOF to be unread. > > What do you think?
I really doubt our ability to get it right. Consider that we have code that accesses the buffer directly, binary and textual ports, etc etc... I don't think we're going to get this right. Fixing this would also have complexity and performance costs as well. Maybe if it is somehow confined to scm_peek_char and scm_fill_input it could be doable. Andy -- http://wingolog.org/
