Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:56866
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain inbox.lv designates 89.111.3.82 as permitted sender)
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Date: Sun, 11 Dec 2011 02:59:45 +0200
Message-ID: <C5AADC70-04B2-4682-9C1B-86BF9E0997AF@inbox.lv>
To: internals@lists.php.net
Mime-Version: 1.0 (Apple Message framework v1084)
Subject: Local time zone
From: chortos@inbox.lv (Oleg Oshmyan)

PHP is used for server-side software that needs to use the remote
client's time zone and for distributed software potentially running on
geographically dispersed servers that needs to use a common time zone,
and in these cases there is no doubt that the time zone should be
manually specified and that the default should be universally constant if
it exists at all. However, PHP is also used for utilities that people run
on their personal machines, and in most cases they _want_ to use the
current system time zone, whatever it is. PHP 5.3 provides a way
to at least guess the current system time zone:

    date_default_timezone_set(@date_default_timezone_get());

PHP 5.4, as currently planned, removes this ability and does not add any
other way to get the system time zone. First, let me ask: is this right
or does another way exist? Second, if no other way exists, I urge that
the guessing algorithm is added back in or split out into a separate
function, say, date_system_timezone_get. Third, I propose improvements
to the guessing algorithm on UNIX:

* The tzname C variable can be used to get two abbreviations for the
  current zone (typically the standard one and the DST one for zones
  where DST is used), which allows to improve the guess compared to using
  just one abbreviation; for example, the time zone in London in winter
  will be guessed as Europe/London rather than UTC.

* /etc/localtime is often a symbolic link to or a copy of
  /usr/share/zoneinfo/<time zone identifier>. In this case this time zone
  identifier can be considered another candidate just like the values
  of date.timezone and TZ.

* This requires more effort, but ideally PHP should just have a special
  time zone named something like 'System' that would use /etc/localtime
  instead of any built-in time zone data, just like the localtime
  C function does when the TZ environment variable is empty.

I am willing to work on patches but I suppose some consensus should be
reached first.

-- 
Oleg