From: "Clément Pit--Claudel" <clement.pit@gmail.com>
To: Joost Kremers <joostkremers@fastmail.fm>
Cc: Emacs developers <emacs-devel@gnu.org>
Subject: Re: RFC: String interpolation
Date: Thu, 8 Dec 2016 13:37:43 -0500 [thread overview]
Message-ID: <0e6143f6-456b-5086-db27-439df4a5be27@gmail.com> (raw)
In-Reply-To: <87r35iwkg7.fsf@fastmail.fm>
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On 2016-12-08 09:43, Joost Kremers wrote:
>> (let ((password "letmein")) (fmt "The password is ${password}")) ⇒
>> "The password is letmein"
>
> Why the {}? Is there any context in which $<expr> is ambiguous such
> that ${<expr>} is needed to resolve it? Other than vectors, I mean
Yes, unfortunately: you can include virtually anything in a Lisp variable name.
(let* ((a 1)
(b 2.0)
(a/b (/ a b)))
(fmt "$a/$b = ${a/b}"))
> I honestly must say I find these last two very confusing. I would
> simply write:
>
> (fmt "Today is $(format-time-string \"%Y-%m-%d\" current-time)).")
>
> The escaped double quotes are not perfect, but I find this much more
> readable and more pleasant to look at.
I really dislike the escaped quotes, but it might just be me :)
This was inspired from Python's per-type format string, but I'm open to better syntax suggestions :)
> Perhaps you should also look at abo-abo's hydra package, since he
> does basically the same thing in his hydra doc strings. AFAICT, it
> works this way: % starts a placeholder, ` marks the start of the
> expression. If the expression is an s-expr, you can leave out the `.
Thanks for the reference! Do you know how it knows where to stop after a backtick?
> So, summarized:
>
> - %<expr> : format the value of <expr> where <expr> can be a symbol
> or an s-expr, possibly also a vector or a string (somewhat
> superfluously...)
>
> - %<fspec>`<expr> : format <expr> according to <fspec>.
>
> Of course, It might be easier to use a different symbol for %, I
> don't know. I have nothing against using $.
Thanks, that's a nice syntax too. I used $ based on a quick review of https://en.wikipedia.org/wiki/String_interpolation . I'm a bit worried about the lack of delimiter after `, though; maybe it would help to see what the example above (with $a/$b and $a/b) would look like in that syntax.
>> fmt expands the strings at compile time (so they must be constant
>> strings).
>
> I've occasionally appreciated the fact that I can pass a dynamically
> created format string to `format'... ;-) Ok, I could always use
> `format' in such cases.
Yes; otherwise, fmt becomes a thinly veiled eval, and that isn't great.
Cheers and thanks for the feedback!
Clément.
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next prev parent reply other threads:[~2016-12-08 18:37 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-08 1:13 RFC: String interpolation Clément Pit--Claudel
2016-12-08 8:27 ` Andreas Schwab
2016-12-08 8:38 ` Joost Kremers
2016-12-08 9:05 ` Philippe Vaucher
2016-12-08 18:25 ` Clément Pit--Claudel
2016-12-08 9:02 ` Philippe Vaucher
2016-12-08 18:22 ` Clément Pit--Claudel
2016-12-08 14:43 ` Joost Kremers
2016-12-08 18:37 ` Clément Pit--Claudel [this message]
2016-12-08 20:04 ` Stefan Monnier
2016-12-09 8:57 ` Joost Kremers
2016-12-08 15:51 ` Drew Adams
2016-12-08 18:21 ` Clément Pit--Claudel
2016-12-08 20:38 ` Richard Stallman
[not found] ` <<E1cF5SK-0000HO-EL@fencepost.gnu.org>
2016-12-08 22:04 ` Drew Adams
2016-12-08 19:05 ` Stefan Monnier
2016-12-08 19:31 ` Clément Pit--Claudel
2016-12-08 21:31 ` Stefan Monnier
2016-12-10 16:01 ` Clément Pit--Claudel
2016-12-09 19:19 ` Ted Zlatanov
2016-12-09 22:45 ` Clément Pit--Claudel
2016-12-11 2:53 ` Ted Zlatanov
2016-12-11 18:46 ` Lars Ingebrigtsen
2016-12-11 18:56 ` Clément Pit--Claudel
2016-12-11 19:34 ` Lars Ingebrigtsen
2016-12-11 17:38 ` Stefan Monnier
2016-12-11 17:53 ` Clément Pit--Claudel
2016-12-10 14:11 ` Lars Ingebrigtsen
2016-12-10 14:25 ` Clément Pit--Claudel
2016-12-10 15:39 ` Lars Ingebrigtsen
2016-12-10 15:49 ` Clément Pit--Claudel
2016-12-10 16:01 ` Yuri Khan
2016-12-10 17:58 ` Clément Pit--Claudel
2016-12-11 17:47 ` Stefan Monnier
2016-12-11 19:31 ` Yuri Khan
2016-12-11 20:12 ` Stefan Monnier
2016-12-11 9:35 ` Richard Stallman
2016-12-11 16:29 ` Clément Pit--Claudel
2016-12-11 18:42 ` Lars Ingebrigtsen
2016-12-12 19:41 ` Richard Stallman
2016-12-11 18:41 ` Lars Ingebrigtsen
2016-12-11 21:05 ` Helmut Eller
2016-12-11 21:26 ` Lars Ingebrigtsen
2016-12-12 2:39 ` Stefan Monnier
2016-12-12 9:44 ` Lars Ingebrigtsen
2016-12-12 13:03 ` Stefan Monnier
2016-12-12 14:47 ` Lars Ingebrigtsen
2016-12-12 15:04 ` Stefan Monnier
2016-12-12 15:26 ` Lars Ingebrigtsen
2016-12-12 17:05 ` Stefan Monnier
2016-12-12 17:12 ` Lars Ingebrigtsen
2016-12-12 17:23 ` Stefan Monnier
2016-12-12 13:40 ` Clément Pit--Claudel
2016-12-12 14:43 ` Lars Ingebrigtsen
2016-12-12 14:54 ` Clément Pit--Claudel
2016-12-12 17:14 ` Stefan Monnier
2016-12-12 17:46 ` Paul Eggert
2016-12-12 18:33 ` Lars Ingebrigtsen
2016-12-12 19:51 ` Ted Zlatanov
2016-12-12 20:41 ` Paul Eggert
2016-12-12 23:40 ` Paul Eggert
2016-12-13 17:42 ` Richard Stallman
2016-12-13 18:05 ` Paul Eggert
2016-12-13 23:55 ` Lars Ingebrigtsen
2016-12-14 0:07 ` Paul Eggert
2016-12-14 0:10 ` John Wiegley
2016-12-14 0:14 ` Lars Ingebrigtsen
2016-12-14 0:17 ` Paul Eggert
2016-12-14 0:26 ` John Wiegley
2016-12-14 1:48 ` Drew Adams
2016-12-14 2:48 ` Elias Mårtenson
2016-12-14 3:33 ` Drew Adams
2016-12-14 3:52 ` Elias Mårtenson
2016-12-14 13:52 ` Lars Brinkhoff
2016-12-14 13:57 ` Lars Brinkhoff
2016-12-14 0:24 ` Drew Adams
2016-12-14 0:21 ` Clément Pit--Claudel
2016-12-14 14:10 ` Lars Ingebrigtsen
2016-12-14 17:00 ` Richard Stallman
2016-12-12 19:43 ` Richard Stallman
2016-12-12 21:11 ` Lars Ingebrigtsen
2016-12-13 17:41 ` Richard Stallman
2016-12-13 17:43 ` Lars Ingebrigtsen
2016-12-14 17:01 ` Richard Stallman
2016-12-13 1:04 ` Ted Zlatanov
2016-12-12 16:39 ` Helmut Eller
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