all messages for Emacs-related lists mirrored at yhetil.org
 help / color / mirror / code / Atom feed
From: Alan Mackenzie <acm@muc.de>
To: Richard Stallman <rms@gnu.org>
Cc: ulm@gentoo.org, emacs-devel@gnu.org
Subject: Re: Why shouldn't we have a #if .... #else .... #endif construct in Emacs Lisp?
Date: Wed, 6 Sep 2023 09:56:34 +0000	[thread overview]
Message-ID: <ZPhM0oknTJU52HT-@ACM> (raw)
In-Reply-To: <E1qdgsQ-0000iT-8p@fencepost.gnu.org>

Hello, Richard.

On Tue, Sep 05, 2023 at 20:58:38 -0400, Richard Stallman wrote:
> [[[ To any NSA and FBI agents reading my email: please consider    ]]]
> [[[ whether defending the US Constitution against all enemies,     ]]]
> [[[ foreign or domestic, requires you to follow Snowden's example. ]]]

>   > For example, in CC Mode there is a chunk of code looking like ....

>   >   (when (fboundp 'electric-indent-local-mode) ; Emacs 24.4 or later.
>   >     (electric-indent-local-mode (if c-electric-flag 1 0)))

>   > , and there are quite a few instances like it.  Here, there is a comment
>   > about which versions are relevant, but that is somewhat unusual.  Note
>   > here that we would have to test both the major and minor version numbers
>   > to do this correctly.

>   > I intend to replace that code with

>   >   (static-if (fboundp 'electric-indent-local-mode) ; Emacs 24.4 or later.
>   >     (electric-indent-local-mode (if c-electric-flag 1 0)))

>   > ..  (hash-if has been renamed static-if.)  It would be more work to
>   > replace it with

>   >   (when (or (> emacs-major-version 24)
>   >             (and (= emacs-major-version 24)
>   > 	         (>= emacs-minor-version 4)))
>   >     (electric-indent-local-mode (if c-electric-flag 1 0)))

> If you want to have a conditional about version mumbers,
> I think that is the right way to write it.

Originally, I wasn't really thinking about version numbers being the
prime use case, but it was easy to use them as an example to get the
discussion going.

> Or, if you want to keep the condition about the availability of
> electric-indent-local-mode, how about keeping the code unchanged

>   >   (when (fboundp 'electric-indent-local-mode) ; Emacs 24.4 or later.
>   >     (electric-indent-local-mode (if c-electric-flag 1 0)))

> and inform the byte compiler that (fboundp 'electric-indent-local-mode)
> can be optimized based on the Emacs version?  This way you won't need
> to change the source code, and we will get the ideal results.

I don't know how to do this.  Early on in the thread, Ulrich Müller
suggested using

    (when (eval-when-compile (fboundp 'electric-indent-local-mode))
       (electric-indent-local-mode (if c-electric-flag 1 0)))

, in which the conditional gets optimised away at compile time.  But
that's still a change in the source code.

>   > static-if is a completely ordinary macro which is 10 lines long
>   > (including doc string), and there's a new section in the elisp manual for
>   > it.

> I think the simplicity of the source code as it will be
> counts for more than the simplicity of a new macro
> which, with my approach, we don't need to add.

We must also take into account the additional complexity of the defmacro
and defun macros (etc.) and the byte compiler to handle the new special
case.  As I've already said, there are just 45 occurrences of
emacs-major-version in the Lisp sources.

> -- 
> Dr Richard Stallman (https://stallman.org)
> Chief GNUisance of the GNU Project (https://gnu.org)
> Founder, Free Software Foundation (https://fsf.org)
> Internet Hall-of-Famer (https://internethalloffame.org)

-- 
Alan Mackenzie (Nuremberg, Germany).



  parent reply	other threads:[~2023-09-06  9:56 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 [this message]
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.
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=ZPhM0oknTJU52HT-@ACM \
    --to=acm@muc.de \
    --cc=emacs-devel@gnu.org \
    --cc=rms@gnu.org \
    --cc=ulm@gentoo.org \
    /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.