Re: Software Engineering News Brief

[mab@dst17.wdl.loral.com (Mark A Biggar)]

In article <dewar.848230046@merv> dewar@merv.cs.nyu.edu (Robert Dewar) writes:
>Fergus said
>  "Gregorian dates aren't tricky, the change-over from other systems is tricky.
>  That's why Paul Eggert suggested supporting Gregorian dates only, even
>  for dates before the Gregorian system was used."
>Well I know that's what he said, but I thought it must be a slip, because
>it is so obviously an undesirable suggestion. To accept dates before the
>18th century without comment or error, and then misinterpret them seems
>highly error prone. Any program that wants to deal with dates before the
>switch over must surely worry for itself about how to deal with this
>situation. If I have a program that tells me the day of the week for any
>date, and I use it to see what day of the week the Magna Carta was signed,
>I either want the right answer, or an error, I certainly do NOT want to
>get an incorrect answer corresponding to what the day would have been
>had the Pope switched over the dates much earlier!

Please note that even the current Ada Year Range of 1901..2099 has the
switch over problem as Russia didn't convert from Julian to Gregorian
until sometime in the 1920's.

--
Mark Biggar
mab@wdl.lmco.com