From: Stefan Monnier via "Emacs development discussions." <emacs-devel@gnu.org>
To: emacs-devel@gnu.org
Subject: Re: Why shouldn't we have a #if .... #else .... #endif construct in Emacs Lisp?
Date: Sat, 02 Sep 2023 19:12:19 -0400 [thread overview]
Message-ID: <jwvzg24rx25.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: CALDnm538f-+5_hxW8vi73N5b1-5A0CRMiq1RM0kAVQan7Te1eQ@mail.gmail.com
>> > In C, we have the very useful conditional compilation
>> > directives introduced by #if or #ifdef, etc., which end at
>> > #end.
>>
>> Those are directives to the C preprocessor and some people say
>> it is a sign of weakness such a thing is even necessary to
>> begin with.
>>
>> Let's see if they are right!
>>
>> What problem do you have? If we can solve it in Elisp, we
>> cannot say those people saying that are wrong.
>>
>
> FWIW, Common Lisp has reader macros to solve the problem:
> http://clhs.lisp.se/Body/24_aba.htm
I don't see why reader macros would be needed here. Reader macros are
useful to introduce funny new shorthands or to avoid *reading* a chunk
of code (e.g. because it uses some unsupported funny syntax) but in the
present case we can read both branches of the `if` just fine, we just
want to throw away one of the two before we macro-expand it.
Stefan
next prev parent reply other threads:[~2023-09-02 23:12 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-28 19:37 Why shouldn't we have a #if .... #else .... #endif construct in Emacs Lisp? Alan Mackenzie
2023-08-28 19:47 ` Ulrich Mueller
2023-08-28 20:06 ` Alan Mackenzie
2023-08-28 21:01 ` Ulrich Mueller
2023-08-28 21:46 ` Alan Mackenzie
2023-08-31 2:07 ` Richard Stallman
2023-08-31 7:50 ` Alan Mackenzie
2023-09-04 1:34 ` Richard Stallman
2023-09-04 10:50 ` Alan Mackenzie
2023-09-04 11:02 ` tomas
2023-09-04 15:19 ` Emanuel Berg
2023-09-04 18:57 ` tomas
2023-09-06 0:58 ` Richard Stallman
2023-09-06 0:58 ` Richard Stallman
2023-09-06 7:28 ` Andreas Schwab
2023-09-06 9:31 ` Alan Mackenzie
2023-09-06 9:56 ` Alan Mackenzie
2023-09-09 0:39 ` Richard Stallman
2023-09-09 10:32 ` Ihor Radchenko
2023-09-10 0:22 ` Richard Stallman
2023-09-10 8:36 ` Ihor Radchenko
2023-09-13 23:53 ` Richard Stallman
2023-09-20 12:59 ` Ihor Radchenko
2023-09-05 0:30 ` Why have a #if .... #else .... #endif construct in Emacs Lisp, when we could make the existing code DTRT unchanged? Richard Stallman
2023-09-05 0:41 ` Emanuel Berg
2023-09-08 17:54 ` Emanuel Berg
2023-09-05 4:37 ` tomas
2023-09-05 5:53 ` Ihor Radchenko
2023-09-05 6:28 ` tomas
2023-09-05 11:06 ` Adam Porter
2023-09-05 11:26 ` Lynn Winebarger
2023-09-05 14:11 ` Alan Mackenzie
2023-09-08 1:01 ` Richard Stallman
2023-09-08 2:45 ` Po Lu
2023-09-10 0:24 ` Richard Stallman
2023-09-05 8:14 ` Why shouldn't we have a #if .... #else .... #endif construct in Emacs Lisp? Ulrich Mueller
2023-08-28 19:53 ` Emanuel Berg
2023-08-29 9:19 ` Alan Mackenzie
2023-08-29 10:36 ` João Távora
2023-08-29 11:09 ` Ihor Radchenko
2023-08-29 11:20 ` João Távora
2023-08-30 20:48 ` Sean Whitton
2023-08-30 20:59 ` João Távora
2023-09-02 23:12 ` Stefan Monnier via Emacs development discussions. [this message]
2023-09-03 0:18 ` Emanuel Berg
2023-09-03 12:27 ` João Távora
2023-08-29 12:54 ` Philip Kaludercic
2023-08-29 13:23 ` Alan Mackenzie
2023-09-02 23:09 ` Stefan Monnier via Emacs development discussions.
2023-08-29 16:28 ` LdBeth
2023-08-29 20:09 ` Stefan Kangas
2023-08-30 10:31 ` Alan Mackenzie
2023-08-30 17:36 ` Stefan Kangas
2023-08-30 18:03 ` Alan Mackenzie
2023-08-30 18:17 ` Stefan Kangas
2023-09-02 15:06 ` Alan Mackenzie
2023-09-02 15:17 ` Eli Zaretskii
2023-09-02 19:43 ` Alan Mackenzie
2023-09-03 4:42 ` Eli Zaretskii
2023-09-03 10:48 ` Alan Mackenzie
2023-09-03 11:02 ` Eli Zaretskii
2023-09-03 13:24 ` Alan Mackenzie
2023-09-02 19:20 ` Philip Kaludercic
2023-09-02 19:37 ` Stefan Kangas
2023-09-02 19:58 ` Alan Mackenzie
2023-09-04 11:12 ` Lynn Winebarger
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=jwvzg24rx25.fsf-monnier+emacs@gnu.org \
--to=emacs-devel@gnu.org \
--cc=monnier@iro.umontreal.ca \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.