S-TAB, <S-tab>, and <backtab>

S-TAB, <S-tab>, and <backtab>

[Hongyi Zhao]

On Ubuntu 20.04.2 LTS, I use the latest git master version of Emacs
compiled by myself. According to the note here [1], I want to bind the
`company-select-previous' command of company package to `Shift Tab',
and tried the following configuration:

;;;
(use-package company
  :demand t
  :bind
  ( :map company-active-map
   [...]

   ("S-TAB" . company-select-previous)
   ;or
   ("<S-tab>" . company-select-previous)
   ;or
   ("<backtab>" . company-select-previous)
   [...]
;;;

But based on my tries, only the following binding is valid:

("<backtab>" . company-select-previous)

[1] https://www.emacswiki.org/emacs/EmacsKeyNotation

Any hints for this problem will be highly appreciated.

Regards
-- 
Assoc. Prof. Hongyi Zhao <hongyi.zhao@gmail.com>
Theory and Simulation of Materials
Hebei Vocational University of Technology and Engineering
No. 473, Quannan West Street, Xindu District, Xingtai, Hebei province

Re: S-TAB, <S-tab>, and <backtab>

[Eric S Fraga]

On Tuesday, 14 Sep 2021 at 18:16, Hongyi Zhao wrote:
>    ("<S-tab>" . company-select-previous)

Untested by this would normally be "S-<tab>" as the S is the modifier
and <tab> the key.

-- 
Eric S Fraga via Emacs 28.0.50 & org 9.4.6 on Debian 11.0

Re: S-TAB, <S-tab>, and <backtab>

[Hongyi Zhao]

On Tue, Sep 14, 2021 at 6:54 PM Eric S Fraga <e.fraga@ucl.ac.uk> wrote:
>
> On Tuesday, 14 Sep 2021 at 18:16, Hongyi Zhao wrote:
> >    ("<S-tab>" . company-select-previous)
>
> Untested by this would normally be "S-<tab>" as the S is the modifier
> and <tab> the key.

Based on my tries, both "<S-tab>" and "S-<tab>" don't work. Both of
these forms have been mentioned in the "Angle-Bracket Notation" of the
emacswiki [1]:

Modifier keys that are part of a key sequence that contains a pseudo
key are sometimes written inside the angle brackets: `<S-tab>’,
`<C-insert>’. And sometimes they are written outside: `S-<tab>’,
`C-<insert>’.

[1] https://www.emacswiki.org/emacs/EmacsKeyNotation

Best Regards
-- 
Assoc. Prof. Hongyi Zhao <hongyi.zhao@gmail.com>
Theory and Simulation of Materials
Hebei Vocational University of Technology and Engineering
No. 473, Quannan West Street, Xindu District, Xingtai, Hebei province

Re: S-TAB, <S-tab>, and <backtab>

[Eric S Fraga]

Okay, I didn't know that.  Sorry for the noise.
-- 
Eric S Fraga via Emacs 28.0.50 & org 9.4.6 on Debian 11.0

Re: S-TAB, <S-tab>, and <backtab>

[Hongyi Zhao]

On Wed, Sep 15, 2021 at 6:27 PM Eric S Fraga <e.fraga@ucl.ac.uk> wrote:
>
> Okay, I didn't know that.

But I still don't understand why my observed behavior is inconsistent
with Emacswiki's description.

> Sorry for the noise.

You're welcome.

Best Regards, Hongyi

Re: S-TAB, <S-tab>, and <backtab>

[Yuri Khan]

On Wed, 15 Sept 2021 at 19:39, Hongyi Zhao <hongyi.zhao@gmail.com> wrote:

> But I still don't understand why my observed behavior is inconsistent
> with Emacswiki's description.

Because Emacs does not receive key combinations directly from the
keyboard. It gets them from a platform-specific lower-level input
subsystem. For example, on X11, XKB translates Shift+Tab to Shift + a
special ISO_Left_Tab pseudo-keysym (see
/usr/share/X11/xkb/symbols/pc). Emacs then translates that to a
<backtab> event.

Re: S-TAB, <S-tab>, and <backtab>

[Hongyi Zhao]

On Thu, Sep 16, 2021 at 12:17 AM Yuri Khan <yuri.v.khan@gmail.com> wrote:
>
> On Wed, 15 Sept 2021 at 19:39, Hongyi Zhao <hongyi.zhao@gmail.com> wrote:
>
> > But I still don't understand why my observed behavior is inconsistent
> > with Emacswiki's description.
>
> Because Emacs does not receive key combinations directly from the
> keyboard. It gets them from a platform-specific lower-level input
> subsystem. For example, on X11, XKB translates Shift+Tab to Shift + a
> special ISO_Left_Tab pseudo-keysym (see
> /usr/share/X11/xkb/symbols/pc). Emacs then translates that to a
> <backtab> event.

Thank you for your explanation, and I confirmed your above comment:

$ egrep -i Tab /usr/share/X11/xkb/symbols/pc
    key  <TAB> {    [ Tab,    ISO_Left_Tab    ]    };

Best, HZ