Re: upload

[Hans Hagen via ntg-context <ntg-context@ntg.nl>]

On 10/22/2021 5:50 PM, Michal Vlasák wrote:
> Hello,
> 
> On Thu Oct 21, 2021 at 8:04 PM CEST, Hans Hagen via ntg-context wrote:
>> I cleaned up some more backend code. There were some mails about dates
>> and such and although the date field in setupinteraction works ok a more
>> drastic overload is doen with directives. The reason is that the fact
>> that we can set the date (and traler) is only because it permits
>> generating pdf files that can be compared. No date as a bad idea anyway.
>>
>> \setupinteraction[title=My Title]
>> % \enabledirectives[backend.date=2034-06-07]
>> \enabledirectives[backend.date=no]
>> \enabledirectives[backend.trailerid=no]
> 
> I checked the backend code and some of the related os functions. I put
> together a patch that hopefully fixes some stuff and doesn't break
> anything. The changes:
> 
> 1) Dates parsed by ConTeXt (function converters.totime), such as those
> that are input to backend.date, now allow specifying seconds and time
> zone information. If there is no timezone the datetime is presumed to be
> in local time, otherwise the datetime is offset by the local / specified
> time zone difference (because ConTeXt outputs these dates as local times
> with local timezone). Additionally both "T" and " " are now allowed as
> date/time separator characters. Thus dates output by ConTeXt can be also
> fed in.

i made the parser a bit more tolerant

"1234-12-30"
"1234/12/30"
"1234-12-30 23:45"
"1234-12-30 23:45:16"
"1234-12-30  23:45:16"
"1234-12-30T23:45:16+01:00"
"1234-12-30 23:45:16-02:00"
"1234-12-30 23:45:16+05:00"
"1234-12-30 23:45:16 05:00"
"1234-12-30  23:45:16  05:00"

(I'll send you the file to check/test)

> 2) Fix the os.timezone function. Previously, it could be wrong around
> midnight, which I discovered only by chance. The trick is lifted from
> http://lua-users.org/wiki/TimeZone, which I hope is OK. The before and
> after (I am at +02:00):
> 
>      os.localtime()  2021-10-22 01:44:24
>      os.now()        2021-10-21 23:44:24
>      os.timezone(true)       -22:00
> 
> 
>      os.localtime()  2021-10-22 01:46:23
>      os.now()        2021-10-21 23:46:23
>      os.timezone(true)       +02:00

shouldn't we also offer a -02:00 ? (relative)

> I also extended the interface of os.timezone to accommodate 1), but as
> this is probably a very public interface, I am not sure if these changes
> are OK. If more changes to the interface can be made, I propose to get
> rid of the delta parameter, since it seems like a remnant from the past.

maybe later, i need to check other files

> Some caching can also be introduced, but I again wasn't sure if this
> even would be the final form of the function, so didn't do anything in
> that sense, yet.

i'll adapt it to that

> 3) Don't use %X in time formats. It is specified to be platform
> dependent and we want %H:%M:%S everywhere. Also, it would be nice if
> lpdf-xmp.lmt would use the os.fulltime() function to format dates (like
> back-exp.lmt does), but there are multiple dates with different formats
> and purposes and it is probably too late to change now.

(probably not that harmfull on the platforms we support)

the reason for different times is that i never liked the timezone in 
regular date/time (so only the mandate one had it) but in the end i 
don't care that much about times/date i never look at (i admit that i 
never consult any of this pdf meta data)

> 4) I changed the os.fulltime function, that returns date + time + local
> time zone to output the _local_ time instead of UTC time. This is AFAICT
> the right way to do times. The PDF spec says:
> 
>      If no UT information is specified, the relationship of the specified
>      time to UT shall be considered to be GMT. Regardless of whether the
>      time zone is specified, the rest of the date shall be specified in
>      local time.
> 
>      EXAMPLE: For example, December 23, 1998, at 7:52 PM, U.S. Pacific
>      Standard Time, is represented by the string D:199812231952-08'00
> 
> A test program:
> 
> 
>      \enabletrackers[backend.info]
>      
>      \enabledirectives[backend.date=1234-12-30]                % 1234-12-30T00:00:00+02:00
>      \enabledirectives[backend.date=1234-12-30 23:45]          % 1234-12-30T23:45:00+02:00
>      \enabledirectives[backend.date=1234-12-30 23:45:16]       % 1234-12-30T23:45:16+02:00
>      \enabledirectives[backend.date=1234-12-30T23:45:16+01:00] % 1234-12-31T00:45:16+02:00
>      \enabledirectives[backend.date=1234-12-30 23:45:16-02:00] % 1234-12-31T03:45:16+02:00
>      \enabledirectives[backend.date=1234-12-30 23:45:16+05:00] % 1234-12-31T20:45:16+02:00
>      
>      \starttext
>      dummy text
>      
>      \startluacode
>      print("os.timezone(true)", os.timezone(true)) -- +02:00
>      print("os.fulltime()", os.fulltime())         -- 2021-10-22 17:38:38+02:00
>      print("os.localtime()", os.localtime())       -- 2021-10-22 17:38:38
>      print("os.now()", os.now())                   -- 2021-10-22 15:38:38
>      \stopluacode
>      \stoptext
> 
> I don't claim to know LPEG so please check my work. I also know nothing
> about XMP, so I didn't check that at all, sorry.

i saw a few things but you can check what i patched later (probably this 
weekend)

Thanks
  Hans


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