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Re: System epochs

From:
lane
Date:
September 12, 2000 05:28
Subject:
Re: System epochs
Message ID:
000912075143.1460f@DUPHY4.Physics.Drexel.Edu
Nathan Wiger <nate@wiger.org> wrote:
> I'm writing a prototype for RFC 99, Standardize ALL Perl platforms on
> UNIX epoch, which does some simplistic manipulation of CORE::time to
> return the UNIX epoch on all platforms.
>
> My question is: Are there any system-specific epochs that Perl uses
> other than MacPerl's? If so, what are they?

VMS prior to version 7.0 uses an epoch of 1 Jan 1970, 0:00  *local time*
(not UTC) for the unixy time() function.

In Perl 5 there's code in vms/vms.c that deals with the choice of
epoch, intercepting calls to time()/gmtime() and adjusting
appropriately so even pre-7.0 systems can have a Perl with the
"standard" Unix epoch.

Note that there's also an issue of timezone/DST-support; I wrote code
to handle this for VMS pre 7.0 systems, but it was never incorporated
into Perl 5.

[The native VMS time functions use an epoch of 17 Nov 1858 0:00 (local
time), IIRC ...but they're 64 bit times that will roll over around the
year 31,000 give or take a millenium]
--
 Drexel University       \V                    --Chuck Lane
======]---------->--------*------------<-------[===========
     (215) 895-1545     _/ \  Particle Physics
FAX: (215) 895-5934     /\ /~~~~~~~~~~~        lane@duphy4.physics.drexel.edu



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