From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Tomas Hlavaty <tom@logand.com>
Cc: Andreas Schwab <schwab@linux-m68k.org>,
Arthur Miller <arthur.miller@live.com>,
emacs-devel@gnu.org
Subject: Re: Partial wdired (edit just filename at the point)
Date: Mon, 22 Mar 2021 18:16:59 -0400 [thread overview]
Message-ID: <jwv35wmon6x.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <87tup2ambb.fsf@logand.com> (Tomas Hlavaty's message of "Mon, 22 Mar 2021 22:52:08 +0100")
> ELISP> (eval (byte-compile '(type-of #'(lambda () 42))))
> compiled-function
>
>> And FWIW, I'd like to get to the point where (type-of (lambda () 42))
>> never returns `cons` but always some kind of "function" type instead,
>> indeed.
>
> Do you mean more like the Common Lisp behaviour?
>
> Getting back to the original advice, in compiled code or in such `some
> kind of "function"' future, using #' will make it not possible to
> redefine wdired--preprocess-line in the hook:
No, I was talking about #'(lambda...) not about #'<symbol>.
IOW, I was talking about having `lambda` returning an actual function
object instead of returning a "list that can be treated as a function".
The use of #'<symbol> to refer to the actual symbol (so that it will
change its semantics whenever that symbol's definition is changed) is
much too ingrained in ELisp, I think changing it would introduce a lot
of breakage and I'm not sure what the benefit would be: there's already
`symbol-function` for that.
> I would like to understand when to prefer #' and when '.
Use #' when you refer to a function by name, use ' when you're just
referring to the symbol for some other reason (it might be a face,
a variable's name, some arbitrary constant, ...).
My rule of thumb is to write #'<foo> whenever I could also place here the
content of (symbol-function 'foo), just with a slightly different semantics.
For example, I prefer to write
(defalias 'foo #'bar)
because it does something quite similar to
(defalias 'foo (symbol-function 'bar))
whereas it does something very different from
(defalias (symbol-function 'foo) #'bar)
-- Stefan
next prev parent reply other threads:[~2021-03-22 22:16 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 18:23 Partial wdired (edit just filename at the point) Arthur Miller
2021-03-17 1:18 ` Stefan Monnier
2021-03-17 2:21 ` Arthur Miller
2021-03-17 2:34 ` Stefan Monnier
2021-03-17 13:58 ` Arthur Miller
2021-03-17 14:09 ` Stefan Monnier
2021-03-17 19:56 ` Arthur Miller
2021-03-17 22:40 ` Arthur Miller
2021-03-18 2:10 ` Stefan Monnier
2021-03-18 10:26 ` Arthur Miller
2021-03-18 10:32 ` Thierry Volpiatto
2021-03-18 11:00 ` Arthur Miller
2021-03-18 11:11 ` Thierry Volpiatto
2021-03-18 11:46 ` Arthur Miller
2021-03-23 23:32 ` Michael Heerdegen
2021-03-18 14:21 ` Stefan Monnier
2021-03-19 11:15 ` Arthur Miller
2021-03-19 16:18 ` Stefan Monnier
2021-03-19 20:40 ` Sv: " arthur miller
2021-03-19 21:58 ` Stefan Monnier
2021-03-20 11:23 ` Sv: " arthur miller
2021-03-21 22:17 ` Tomas Hlavaty
2021-03-22 8:12 ` tomas
2021-03-22 12:44 ` Arthur Miller
2021-03-22 14:50 ` tomas
2021-03-22 13:11 ` Stefan Monnier
2021-03-22 20:08 ` Tomas Hlavaty
2021-03-22 20:28 ` Andreas Schwab
2021-03-22 21:00 ` Stefan Monnier
2021-03-22 21:52 ` Tomas Hlavaty
2021-03-22 22:16 ` Stefan Monnier [this message]
2021-03-22 22:39 ` Tomas Hlavaty
2021-03-22 23:27 ` Andreas Schwab
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