From: Alan Mackenzie <acm@muc.de>
To: Michael Heerdegen <michael_heerdegen@web.de>
Cc: 25461@debbugs.gnu.org
Subject: bug#25461: [Patch]: Missing doc strings for "," and ",@".
Date: Thu, 19 Jan 2017 17:58:01 +0000 [thread overview]
Message-ID: <20170119175801.GB3397@acm.fritz.box> (raw)
In-Reply-To: <87lgu7dbyz.fsf@web.de>
Hello, Michael.
On Thu, Jan 19, 2017 at 03:23:32AM +0100, Michael Heerdegen wrote:
> Hi Alan,
> > diff --git a/lisp/emacs-lisp/backquote.el b/lisp/emacs-lisp/backquote.el
> > index 94c561c..86ca010 100644
> > --- a/lisp/emacs-lisp/backquote.el
> > +++ b/lisp/emacs-lisp/backquote.el
> > @@ -247,4 +247,33 @@ backquote-listify
> > tail))
> > (t (cons 'list heads)))))
> > +\f
> > +;; 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.
> > +It can occur only 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 `,@'.
> I don't think this makes it easier for people to understand things.
> This suggests that "," has some kind of meaning per se, that it is a
> macro-like thing, etc, and that pcase somehow redefines it.
Yes. All these things are true, aren't they?
> Of course there is a logic behind pcase's usage of ` and ,. The
> usage of these suggests a mental model for their "meaning". But we
> should not describe our mental models in docstrings. That's only useful
> for people sharing the same model.
I'm not sure I'm following you here. A high level description of a
function necessarily involves a mental model.
> The bindings of variables depend on context. The semantics of functions
> are fluent (advice, local functions). And also the "meaning" of the
> sexps created by ` and , depend on the context - in Lisp, the "meaning"
> of all sexps depends on context. (foo bar) can be a function call or a
> part of a let variable binding or a list or a pcase pattern. It's not
> different for sexps involving `.
` has a specific meaning, and has had a high quality doc string for
ever. , likewise has a specific meaning, but doesn't yet have a doc
string.
In Emacs Lisp, functions generally have well defined context-free
semantics, though there are exceptions.
> So I think we maximally should describe what the reader does with `
> etc., so that people know what to search for in the manual or remember
> what they already had learned.
We don't do that for other functions. A function's doc string should be
a crisp summary of what a function _does_. A doc string which directs
people to a manual, or is so confusing or unspecific that the reader is
forced to open a manual, is a failed doc string.
, has a definite precise function (disregarding its use in pcase for
now). Have you any specific suggestions on how to improve my wording of
its doc string?
> + ((get function 'reader-macro)
> + "a reader macro")
> We don't have reader macros in Emacs.
The reader performs macro-like actions. What is the correct alternative
term for what the reader does with ', `, ,, #', etc.?
> If we had them, we could implement ', ` etc. as reader macros. But
> using this term in H-f is confusing, because it is not used in the
> manual.
What would be a less confusing alternative?
> Regards,
> Michael
--
Alan Mackenzie (Nuremberg, Germany).
next prev parent reply other threads:[~2017-01-19 17:58 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
2017-01-20 0:24 ` Michael Heerdegen
2017-01-19 2:23 ` Michael Heerdegen
2017-01-19 17:58 ` Alan Mackenzie [this message]
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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