On Mon, 12 May 2003, Ralf G. R. Bergs wrote:
> You must be a mathematician specializing in Boolean logic. ;-)
I was once a mathematician, but I never studied Boolean logic in those
days.
> One last question: Do the implicit AND/OR association "weights" ("AND"
> stronger than "OR") apply? I.e. "c OR a AND b" == "c OR (a AND b)"? Or do we
> have a strict left-to-right logic, i.e. "c OR a AND b" == "(c OR a) AND b"?
The ORs and ANDs are just another way of trying to understand what
something means. The implementation is strictly left-to-right. It's all
in the manual:
10.2 Negated items in lists
Items in a list may be positive or negative. Negative items are indicated by a
leading exclamation mark, which may be followed by optional white space. A
list defines a set of items (domains, etc). When Exim processes one of these
lists, it is trying to find out whether a domain, host, address, or local part
(respectively) is in the set that is defined by the list. It works like this:
The list is scanned from left to right. If a positive item is matched, the
subject that is being checked is in the set; if a negative item is matched,
the subject is not in the set. If the end of the list is reached without the
subject having matched any of the patterns, it is in the set if the last item
was a negative one, but not if it was a positive one.
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
