From: René Scharfe Date: Mon, 12 Jun 2017 16:58:13 GMT Subject: Re: [PATCH] strbuf: let strbuf_addftime handle %z and %Z itself Message-ID: In-Reply-To: Am 12.06.2017 um 18:16 schrieb Ævar Arnfjörð Bjarmason: > On Mon, Jun 12, 2017 at 5:12 PM, Junio C Hamano wrote: >> René Scharfe writes: >> >>> Am 07.06.2017 um 10:17 schrieb Jeff King: >>>> On Sat, Jun 03, 2017 at 12:40:34PM +0200, René Scharfe wrote: >>>>> Duplicates strbuf_expand to a certain extent, but not too badly, I >>>>> think. Leaves the door open for letting strftime handle the local >>>>> case. >>>> >>>> I guess you'd plan to do that like this in the caller: >>>> >>>> if (date->local) >>>> tz_name = NULL; >>>> else >>>> tz_name = ""; >>>> >>>> and then your strftime() doesn't do any %z expansion when tz_name is >>>> NULL. >>> >>> Yes, or you could look up a time zone name somewhere else -- except we >>> don't have a way to do that, at least for now. >> >> Is that only "for now"? I have a feeling that it is fundamentally >> impossible with the data we record. When GMTOFF 9:00 is the only >> thing we have for a timestamp, can we tell if we should label it as >> JST (aka Asia/Tokyo) or KST (aka Asia/Seoul)? We could track the time zone on commit, e.g. in a new header. I doubt that the need for showing time zone names will be strong enough to go to that length, though. > It's obviously not perfect for all the reasons mentioned in this > thread, but we already have a timezone->offset mapping in the > timezone_names variable in date.c, a good enough solution might be to > simply reverse that lookup when formatting %Z > > Of course we can never know if you were in Tokyo or Seul from the info > in the commit object, but we don't need to, it's enough that we just > emit JST for +0900 and anyone reading the output has at least some > idea what +0900 maps to. I suspect that there will be different opinions, for cultural and political reasons. > We could also simply replace "%Z" with the empty string, as the the > POSIX strftime() documentation allows for: > http://pubs.opengroup.org/onlinepubs/009695399/functions/strftime.html > ("Replaced by the timezone name or abbreviation, or by no bytes if no > timezone information exists."). Yes, that's what the patch does. René