Re: [TCLCORE] TIP #173, time zones and redundancy

[<ke...@cr...>]

st...@ic... said:
> FWIW, Mac OS X has /usr/share/zoneinfo, and I suspect other *BSDs do
> as  well. There is nothing Linux specific here

OK, so we add it to the configurator for the *BSDs as well.  By the way,
I rather expected that, because the Olson time zone codes are incorporated
into glibc.  Systems where the libc is not glibc are rather more variable.

This discussion is leading us to the following set of time zone
data that the configurator will manage:

   :localtime
        always available, implemented in C
   :UTC
        always available, this time zone is built in to the code
   Posix time zone specs like EST5EDT or 
   <EST>05:00<EDT>04:00.M4.1.0/02:00,M10.5.0/02:00
        always available
   ISO8601 time zones like -0500
        always avaliable
   Military time zones like 'R' (any single letter other than 'J')
        always available
   Time zones in the form :Continent/Territory (e.g., :America/New_York)
        Availability depends on the presence of Olson's zoneinfo
        or Tcl's tzdata.  It will be possible to configure the build
        to use tzdata, zoneinfo, or neither.  The default configuration
        will use zoneinfo on systems that are known to have it,
        including Linux, MacOSX and the other BSD-derived systems,
        and possibly Solaris.  It will use Tcl's tzdata on ones that
        aren't known to have zoneinfo.  (This method may be overridden
        in the configurator  in order to use newer tzdata or to deal 
        with Daylight Saving Time beyond Y2038.)  Embedded builds may
        elect to include neither zoneinfo nor tzdata.

It's still the case that if no time zone is specified, the time zone
will be determined by (in order of preference):
    $env(TCL_TZ)
    $env(TZ)
    (on Windows) the registry entry
        HKLM\System\CurrentControlSet\Control\TimeZoneInformation
    ":localtime" if all else fails

--
73 de ke9tv/2, Kevin KENNY   GE Corporate Research & Development
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