bug#71572: [PATCH] seconds-to-string-approximate

[Eli Zaretskii <eliz@gnu.org>]

> From: JD Smith <jdtsmith@gmail.com>
> Date: Sat, 22 Jun 2024 22:16:40 -0400
> Cc: Eli Zaretskii <eliz@gnu.org>,
>  71572@debbugs.gnu.org,
>  Adam Porter <adam@alphapapa.net>,
>  jonas@bernoul.li
> 
> > Why not look at what mastodon.el does, as the comment in seconds-to-string suggests? For example, mastodon-tl--human-duration lets you specify whatever resolution you want, instead of limiting you to either 0.5 or 1  as in the proposed patch.
> 
> I see that mastodon is a package in ELPA, so doesn't satisfy the need in core.  I took a look at this function.  The RESOLUTION mentioned is not equivalent to the HALF argument, it is the minimum resolution in seconds.  So setting it to e.g. 3600 results in truncating to the hour, but changes nothing below the hour.  Setting it to the number of seconds in a year gives something quite similar to magit--age (though I notice the mastodon function truncates, instead of rounds; see, e.g., 2.98y in the table below).
> 
> Here's a comparison among:
> 
> - the current seconds-to-string
> - mastodon-tl--human-duration
> - mastodon with a 3600s resolution
> - mastodon with 1yr "resolution"
> - the new seconds-to-string with option READABLE=t
> - new seconds-to-string with abbreviated units and half unit resolution
> 
>   Delay (s)      s-to-s            mastodon    mastodon (3600s)    mast (1yr)  s-to-s (rdb)  s-to-s (rdb=abbrev, half)
>         0.5    450.00ms               0 sec               0 sec         0 sec     0 seconds  ½s
>         1.0       1.03s               1 sec               1 sec         1 sec      1 second  1s
>         2.4       2.38s              2 secs              2 secs        2 secs     2 seconds  2½s
>         5.5       5.48s              5 secs              5 secs        5 secs     5 seconds  5½s
>        12.6      12.59s             12 secs             12 secs       12 secs    13 seconds  12½s
>        29.0      28.96s             28 secs             28 secs       28 secs    29 seconds  29s
>        66.6      66.62s               1 min               1 min         1 min      1 minute  1m
>       153.2       2.55m              2 mins              2 mins        2 mins     3 minutes  2½m
>       352.4       5.87m              5 mins              5 mins        5 mins     6 minutes  6m
>       810.5      13.51m             13 mins             13 mins       13 mins    14 minutes  13½m
>      1864.2      31.07m             31 mins             31 mins       31 mins    31 minutes  31m
>      4287.6      71.46m     1 hour, 11 mins              1 hour        1 hour        1 hour  1h
>      9861.6       2.74h    2 hours, 44 mins             2 hours       2 hours       3 hours  2½h
>     22681.6       6.30h    6 hours, 18 mins             6 hours       6 hours       6 hours  6½h
>     52167.8      14.49h   14 hours, 29 mins            14 hours      14 hours      14 hours  14½h
>    119985.9       1.39d      1 day, 9 hours      1 day, 9 hours         1 day         1 day  1½d
>    275967.5       3.19d     3 days, 4 hours     3 days, 4 hours        3 days        3 days  3d
>    634725.2       7.35d              1 week              1 week        1 week        1 week  1w
>   1459867.9      16.90d     2 weeks, 2 days     2 weeks, 2 days       2 weeks       2 weeks  2½w
>   3357696.2      38.86d     1 month, 1 week     1 month, 1 week       1 month       1 month  1½M
>   7722701.2      89.38d   2 months, 4 weeks   2 months, 4 weeks      2 months      3 months  3M
>  17762212.9     205.58d   6 months, 3 weeks   6 months, 3 weeks      6 months      7 months  7M
>  40853089.6       1.29y    1 year, 3 months    1 year, 3 months        1 year        1 year  1½Y
>  93962106.0       2.98y  2 years, 11 months  2 years, 11 months       2 years       3 years  3Y
> 216112843.8       6.85y  6 years, 10 months  6 years, 10 months       6 years       7 years  7Y
> 497059540.7      15.75y  15 years, 9 months  15 years, 9 months      15 years      16 years  16Y

Basically, this shows that:

 . mastodon truncates where seconds-to-string rounds
 . seconds-to-string lacks the "1 hour 11 min" output format
 . seconds-to-string sometimes produces inaccurate results, as in
   5.5 => 5.48s

The last item worries me: can we fix this, please?
The second item sounds like a useful feature, so maybe an optional
behavior could provide it as well?

Thanks.