From: Juri Linkov <juri@linkov.net>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: emacs-devel@gnu.org
Subject: Re: master ce4ec17: Fix display-buffer-override-next-command to call action only once (bug#39722)
Date: Wed, 24 Jun 2020 02:45:19 +0300 [thread overview]
Message-ID: <87zh8txsdc.fsf@mail.linkov.net> (raw)
In-Reply-To: <jwvr1u68mci.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Tue, 23 Jun 2020 00:09:06 -0400")
>>> I'm not sure how. I think `C-x 4 4` followed by `C-u` will work thanks
>>> to the (eq this-command command) check (because
>>> `prefix-command-preserve-state` does (setq this-command last-command)),
>>> but I don't think the reverse will work.
>> Could you give an example of a key sequence where this might not work?
>
> `C-u C-x 5 5 C-x =` won't display the extra info requested by the `C-u`.
>
> You can still get it with `C-x 5 5 C-u C-x =`, but the user shouldn't
> have to remember in which order prefix commands need to be entered.
The feature was intentionally designed this way for several reasons:
1. it should be easier for the users to build the key sequence
when the prefix is in front of the main command key sequence,
not before the command that requests a new window/frame;
2. to allow adding arguments to the commands `C-x 4 4` and `C-x 5 5`.
The design was based on the existing command `windmove-display-in-direction`
where the prefix arg can be given to not select the displayed window.
Similarly, the prefix arg could be added to `C-x 4 4` and `C-x 5 5`
to request displaying the buffer in another window/frame,
but not to select the displayed window.
Then `C-u C-x 5 5 C-u C-x =` will display the Help buffer in another frame
without selecting it.
>> display-buffer-overriding-action has exactly the same format as
>> display-buffer-fallback-action, and display-buffer-fallback-action
>> holds a list of actions:
>>
>> (defconst display-buffer-fallback-action
>> '((display-buffer--maybe-same-window ;FIXME: why isn't this redundant?
>> display-buffer-reuse-window
>> display-buffer--maybe-pop-up-frame-or-window
>> display-buffer-in-previous-window
>> display-buffer-use-some-window
>> ;; If all else fails, pop up a new frame.
>> display-buffer-pop-up-frame))
>
> Look again! This is not a list of functions: it's a cons cell whose car
> is a list of functions.
It seems currently it works because no other code tries to modify
display-buffer-overriding-action, but really functions should be added
to the car of display-buffer-overriding-action, or maybe even better
not to add but replace display-buffer-overriding-action with own value.
>> Incidentally, the echo area feedback and the extra transient keymap
>> is exactly what is currently discussed for project-switch-project
>> where `C-x p p` displays a short menu in the echo area and reads keys
>> to run commands from the project.el prefix keymap.
>
> I was referring to the each area info also displayed by `C-u`, via
> `prefix-command-echo-keystrokes-functions`. Nothing fancy like a menu:
> just a brief mention to reflect the fact that a prefix command is "about
> to be applied".
Currently `C-x 5 5` just displays the message before the next command:
"Display next command buffer in a new frame..."
but using `prefix-command-echo-keystrokes-functions` it could display
"[other-frame]" like other-frame-window does for every following key press.
next prev parent reply other threads:[~2020-06-23 23:45 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200621233622.23590.68753@vcs0.savannah.gnu.org>
[not found] ` <20200621233623.C811520A26@vcs0.savannah.gnu.org>
2020-06-22 0:29 ` master ce4ec17: Fix display-buffer-override-next-command to call action only once (bug#39722) Stefan Monnier
2020-06-22 0:35 ` Juri Linkov
2020-06-22 3:38 ` Stefan Monnier
2020-06-23 0:01 ` Juri Linkov
2020-06-23 4:09 ` Stefan Monnier
2020-06-23 23:45 ` Juri Linkov [this message]
2020-06-24 5:14 ` Stefan Monnier
2020-06-24 23:58 ` Juri Linkov
2020-06-28 22:14 ` Juri Linkov
2020-06-29 12:29 ` Stefan Monnier
2020-06-29 22:43 ` Juri Linkov
2020-06-30 2:48 ` Stefan Monnier
2020-06-30 8:52 ` Kévin Le Gouguec
2020-06-30 21:31 ` Juri Linkov
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