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Re: encode-time vs decode-time
From: |
Lars Ingebrigtsen |
Subject: |
Re: encode-time vs decode-time |
Date: |
Wed, 31 Jul 2019 21:03:07 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
Paul Eggert <address@hidden> writes:
>> this is very confusing indeed
> To some extent the confusion is inherent: there are a lot of useful
> ways to represent and manipulate times, and people unfamiliar with the
> issues will find this complexity confusing. That being said, it would
> be good to simplify the Emacs API for time without significantly
> hurting functionality or compatibility.
>
> So, how about this idea. First we go along the lines of your
> suggestion, and change decode-time to return a ninth slot with a
> numerator-denominator pair that preserves all the precision of its
> argument. Second, we change (encode-time TIME t) so that it also
> preserves all the precision of its argument. This will cause
> (encode-time (decode-time TIME) t) to return a value equivalent to
> TIME, which will simplify roundtripping.
I think this sounds workable, but I think it would be even better to
introduce some new functions instead of overloading our poor encode-time
function.
When you did the major sanitation in this area last year (which was
overall a very good thing), you did stuff like
- (now (string-to-number (format-time-string "%s")))
+ (now (encode-time nil 'integer))
and
- (now (float-time))
+ (now (encode-time nil 'integer))
and many similar transforms. The new code is definitely better than the
old code, and it's not more cryptic than it used to be, really.
However, I think it would have been even better to introduce a new
function to enable people who are unfamiliar with how this all works to
just read the code and understand what it's doing.
So I think the things up above there should really be calls to a new
function `get-current-time', that returns the same thing as
`(encode-time nil 'integer)'. It should default to `integer', but can
have an optional argument that says what form of "internal second time
format" to return (i.e., `list', `t').
And then, finally, I think there should be a function to convert between
these "internal second time" formats. Like... `convert-time-format',
which would be like `(encode-time time 'list)' (etc).
And then leave encode-time/decode-time a simple pair that would do
nothing but convert between "internal second time format" and "decoded
time format".
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
- Re: Support for sub-second time in decoded time, (continued)
- encode-time vs decode-time, Stefan Monnier, 2019/07/29
- Re: encode-time vs decode-time, Lars Ingebrigtsen, 2019/07/30
- Re: encode-time vs decode-time, Andy Moreton, 2019/07/30
- Re: encode-time vs decode-time, Lars Ingebrigtsen, 2019/07/30
- Re: encode-time vs decode-time, Paul Eggert, 2019/07/30
- Re: encode-time vs decode-time, Paul Eggert, 2019/07/30
- Re: encode-time vs decode-time,
Lars Ingebrigtsen <=
- Re: encode-time vs decode-time, Stefan Monnier, 2019/07/31
Re: Support for sub-second time in decoded time, Eli Zaretskii, 2019/07/29
Re: Support for sub-second time in decoded time, Paul Eggert, 2019/07/29