From: Alan Mackenzie <acm@muc.de>
To: Noam Postavsky <npostavs@users.sourceforge.net>
Cc: 25461@debbugs.gnu.org
Subject: bug#25461: [Patch]: Missing doc strings for "," and ",@".
Date: Thu, 19 Jan 2017 18:36:39 +0000 [thread overview]
Message-ID: <20170119183639.GC3397@acm.fritz.box> (raw)
In-Reply-To: <CAM-tV-9jQd9Vta-HOsS9NZuLWu4O5=s2z4tNJ0Lr_6hLYCMYug@mail.gmail.com>
Hello, Noam.
On Thu, Jan 19, 2017 at 01:10:24PM -0500, Noam Postavsky wrote:
> On Thu, Jan 19, 2017 at 12:37 PM, Alan Mackenzie <acm@muc.de> wrote:
> >> > +;; Give `,' and `,@' documentation strings which can be examined by C-h f.
> >> > +(put '\, 'function-documentation
> >> > + "`,' signals that the next form should be evaluated and inserted.
[ .... ]
> I agree backquote is the primary use, it's reasonable to emphasize that.
> Because "," isn't a macro, it doesn't have any semantics. It's
^^^^
> misleading to suggest that it does.
We could degenerate into a long silly discussion about what "have" means.
, evaluates the form it precedes, and inserts it into the containing
list. That's semantics enough for me.
> >> > +It can occur only in `\\=`' constructs.
> >> This isn't true.
> > In what sense is it not true? I've never seen a comma used otherwise in
> > a lisp program. What misunderstanding could it cause in a (relatively
> > new) Lisp hacker reading it?
> In the sense that it's possible to write a macro that could treat the
> "," differently. I don't know of any that currently do*, but that's
> just convention and should be documented as such.
OK, I've toned down that part of the doc string. (See below.)
> * `use-package' once handled unmatched "," as signifying eager
> evaluation, but it no longer does that.
How about this, then:
"`,' signals that the next form should be evaluated and inserted.
It occurs in `\\=`' constructs.
For example:
b => (ba bb bc) ; assume b has this value
\\=`(a ,b c) => (a (ba bb bc) c) ; insert the value of b
See also `\\=`' and `,@'.
(Note that ``' constructs (including `,'s) sometimes have different
semantics. This occurs, for example, with the macro `pcase' and other
macros with similar names.)
?
--
Alan Mackenzie (Nuremberg, Germany).
next prev parent reply other threads:[~2017-01-19 18:36 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-16 21:22 bug#25461: Missing doc strings for "," and ",@" Alan Mackenzie
2017-01-17 19:34 ` Glenn Morris
2017-01-17 19:56 ` Alan Mackenzie
2017-01-17 20:36 ` Andreas Schwab
2017-01-17 20:41 ` Alan Mackenzie
2017-01-17 20:53 ` Andreas Schwab
2017-01-18 1:44 ` Michael Heerdegen
2017-01-18 19:28 ` Alan Mackenzie
[not found] ` <handler.25461.B.148460180922707.ack@debbugs.gnu.org>
2017-01-18 19:43 ` bug#25461: [Patch]: " Alan Mackenzie
2017-01-19 0:16 ` npostavs
2017-01-19 17:37 ` Alan Mackenzie
2017-01-19 18:10 ` Noam Postavsky
2017-01-19 18:36 ` Alan Mackenzie [this message]
2017-01-20 0:24 ` Michael Heerdegen
2017-01-19 2:23 ` Michael Heerdegen
2017-01-19 17:58 ` Alan Mackenzie
2017-01-20 0:12 ` Michael Heerdegen
2017-01-20 16:58 ` Alan Mackenzie
2017-01-21 2:26 ` Michael Heerdegen
2017-01-21 15:56 ` Alan Mackenzie
2017-01-21 20:46 ` bug#25461: [Patch #2]: " Alan Mackenzie
2017-01-24 1:58 ` Michael Heerdegen
2017-01-24 19:43 ` Alan Mackenzie
2017-01-24 4:01 ` npostavs
2017-01-24 19:39 ` Alan Mackenzie
2017-01-24 20:00 ` Noam Postavsky
2017-01-23 19:09 ` bug#25461: [Patch]: " Alan Mackenzie
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