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To: Oleg Oshmyan <chortos@inbox.lv>
cc: PHP Developers Mailing List <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Local time zone
From: derick@php.net (Derick Rethans)

On Sun, 11 Dec 2011, Oleg Oshmyan wrote:

> * 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.

It's a guess, and that's the problem. Guessing makes up for odd and 
strange bugs if it's not 100% accurate (which it isn't). 

> * /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 might work on some distrbutions, but not nearly on all. And 
definitely not on Windows. On Debian it's not a symlink for example.

> * 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.

That's a really bad idea, as we've discussed before on this list.

cheers,
Derick