Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.std.c > #6465

Re: C23: asctime is obsolescent

Show all headers | View raw

On 03/01/2023 01:47, Keith Thompson wrote:
> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>>> In the latest C23 draft:
>>>      https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3047.pdf
>>> the descriptions of the __DATE__ and __TIME__ macros refer to the
>>> asctime() function.
>>>
>>> That's not new.  What's new is that asctime() is deprecated.
>>>
>>> Referring to a deprecated function isn't really a problem, but if
>>> asctime() is actually removed in a future standard the descriptions of
>>> __DATE__ and __TIME__ will need to be updated.
>>>
>>> It would also be nice to have a new macro that expands to the current
>>> date in the form "YYYY-MM-DD".  I do not suggest changing the behavior
>>> of __DATE__, but perhaps something like __ISODATE__ could be added.
>>> Question:  If this is done, should __DATE__ be deprecated?
>>
>> It seems pointless to add __ISODATE__ if __DATE__ is retained, and
>> worse than pointless to add __ISODATE__ and then remove __DATE__.
>>
>> Similar comments apply to __TIME__, which also refers to asctime().
> 
> I agree that __DATE__ should not be removed.  On further thought, I
> don't think it should be deprecated.  The format it uses, "Jan  2 2023",
> is too region-specific, but presumably some C code uses it, and it can't
> be fully re-implemented in user code.
> 
> If asctime() is removed in a future standard, then the descriptions of
> __DATE__ and __TIME__ would have to be updated.  I offer no opinion on
> whether asctime() *should* be deprecated.
> 
> I don't see how "Similar comments" would apply to __TIME__.  I'm not
> suggesting changing it, just updating the description.
> 
> I'm at a loss to understand why you think adding __ISODATE__ would be
> pointless.  If I'm going to include the compilation date in my own code,
> I'd much rather use "YYYY-MM-DD" than "Mmm dd yyyy", assuming both are
> available.  If you prefer the latter, you can still use it.
> 

IMHO, introducing __ISODATE__ and then deprecating __DATE__ would be the 
right move.

Note that deprecating __DATE__ does not mean removing it from the 
standard, and certainly not from C compilers.  It simply means that 
__ISODATE__ is the preferred way to put a "compile date" into the code, 
while __DATE__ is kept for backwards compatibility.  And I think most 
people will agree that __ISODATE__ gives a more useful, parseable, 
flexible and international format than the very USA-centric, 
English-centric, mixed-endian and mixed numeric/text format of __DATE__.

As for deprecating asctime(), I'd vote for that.  It is such a very 
specific and very ugly format - AFAIK it is not common even in the USA 
to put the time in the middle of date.  And as described in the 
standard, it is nothing that you can't do with a simple sprintf() call.


Another option for build timestamps would be to introduce a macro 
"__BUILD_TM__" which would generate data suitable for :

	const struct tm build_tm = __BUILD_TM__;

Then people could get the build time and date in a manner suitable for 
printing version information in whatever format suits their needs.


(Personally, I do not use any of these in my code - it is important to 
me that my builds are reproducible.  While build timestamps would be 
nice, reproducibility overrides that for me.)

Back to comp.std.c | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

C23: asctime is obsolescent Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-11-23 18:12 -0800
  Re: C23: asctime is obsolescent Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-01-02 08:11 -0800
    Re: C23: asctime is obsolescent Richard Damon <Richard@Damon-Family.org> - 2023-01-02 12:11 -0500
      Re: C23: asctime is obsolescent Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-01-29 10:33 -0800
        Re: C23: asctime is obsolescent Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-01-29 16:49 -0800
          Re: C23: asctime is obsolescent Pete Forman <petef4+usenet@gmail.com> - 2023-01-30 23:23 +0000
          Re: C23: asctime is obsolescent Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-07-20 10:11 -0700
            Re: C23: asctime is obsolescent Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-07-20 15:04 -0700
              Re: C23: asctime is obsolescent Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-13 15:26 -0700
                Re: C23: asctime is obsolescent Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-08-13 16:47 -0700
                Re: C23: asctime is obsolescent Jakob Bohm <jb-usenet@wisemo.com.invalid> - 2023-08-17 21:18 +0200
                Re: C23: asctime is obsolescent Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-08-17 13:14 -0700
                Re: C23: asctime is obsolescent Jakob Bohm <jb-usenet@wisemo.com.invalid> - 2023-08-18 01:26 +0200
                Re: C23: asctime is obsolescent Pete Forman <petef4+usenet@gmail.com> - 2023-08-21 17:42 +0100
                Re: C23: asctime is obsolescent Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-29 02:37 -0700
    Re: C23: asctime is obsolescent Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-01-02 16:47 -0800
      Re: C23: asctime is obsolescent David Brown <david.brown@hesbynett.no> - 2023-01-03 09:40 +0100
      Re: C23: asctime is obsolescent Pete Forman <petef4+usenet@gmail.com> - 2023-01-03 15:15 +0000
        Re: C23: asctime is obsolescent Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-01-03 10:35 -0800
        Re: C23: asctime is obsolescent Phil Carmody <pc+usenet@asdf.org> - 2023-01-04 18:22 +0200
          Re: C23: asctime is obsolescent James Kuyper <jameskuyper@alumni.caltech.edu> - 2023-01-04 15:04 -0500
      Re: C23: asctime is obsolescent Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-01-29 10:43 -0800
  Re: C23: asctime is obsolescent Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-01-02 08:20 -0800
  Re: C23: asctime is obsolescent Kaz Kylheku <864-117-4973@kylheku.com> - 2023-07-20 17:29 +0000
    Re: C23: asctime is obsolescent Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-07-20 15:20 -0700

csiph-web