On Mon, 21 Jun 1999 yann.golanski@??? wrote:
> This is a patch to exim-3.02 that adds one function to the expand.c
> routines.
>
> The function is a `formated hash' (fh) that takes a number of options:
> ${formatedhash_retval_sept_hrange_str}
> where
> retval is an int, defining the number of output returned. Should be
> smaller than 100.
> sept is a list of characters, separated by `;', that will be used
> to separate the hashed part.
> hrange is a list of ints, separated by `;', that is the range of
> the hash.
> str is the string that will be hashed.
Thanks for the submission, but I have several comments:
(1) Is this a replacement for, or in addition to, the previous new hash
function you supplied?
(2) The syntax of all other expansion operators uses a colon before the
string to be operated on, but you have used an underscore. I don't like
the inconsistency.
(3) This function returns a small number; is there any good reason why
this is any better than a single character out of (say) the 62 letters
and digits? I realize that the answer might be "I need more than 62",
but I see you have limited it to 100.
(4) Is there any benefit from packing up several hashes into one call
instead of just calling a simpler hash function several times? The
interface seems very complicated to me.
> For example:
> ${local_part} = fred@???
> /var/spool/${formatedhash_3_/;/;/_10;20;30_${local_part}}/Mailbox
> would return 3 hash numbers based on ${local_part} separated by `/'. The
> first hashed number returned would be mapped from 0 to 9, the second from 0
> to 19 and the third from 0 to 29. The returned line would look like:
> /var/spool/7/17/27/Mailbox
What benefit does this give over
/var/spool/${hash_1_10:$local_part}/${hash_1_20:$local_part}/${hash_1_30:$local_part}/Mailbox
which might return
/var/spool/h/r/B/Mailbox
other than perhaps the quality of the hash function?
Basically, I am worrying about code bloat and specification
complication.
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
--
*** Exim information can be found at
http://www.exim.org/ ***
