Re: Repeat lambda (was: Some minor suggestions to Tab Bar)

[Zhiwei Chen <chenzhiwei03@kuaishou.com>]

> On Mar 24, 2021, at 2:30 AM, Juri Linkov <juri@linkov.net> wrote:
> 
>>> (defvar tab-bar-move-repeat-map
>>> (let ((map (make-sparse-keymap)))
>>>   (define-key map "m" 'tab-move)
>>>   (define-key map "M" (lambda ()
>>>                         (interactive)
>>>                         (tab-move -1)))
>>>   map)
>>> "Keymap to repeat tab move key sequences `C-x t m m'.
>>> Used in `repeat-mode'.")
>>> (put 'tab-move 'repeat-map 'tab-bar-move-repeat-map)
>> 
>> One nitpicking is that `C-x t m M m’ is not allowed
>> since `(tab-move -1)` hasn’t a `repeat-map’ property.
>> Maybe name it tab-move-prev and set the property?
> 
> This can't be a general solution since there are other keymaps
> where repeating lambda is required.
> 
> For example, other-window-repeat-map currently has no keybinding
> that could switch to navigating windows in the opposite direction.
> There were proposals to bind it to "O", but since there is no such
> command as "previous-window" to cycle windows backwards,
> using a lambda is required, but currently this doesn't work:
> 
>  (define-key other-window-repeat-map "O"
>    (lambda ()
>      (interactive)
>      (other-window -1)))
> 
> Stefan already asked about this, but I had no idea
> how it could be improved.  Now I tried to set
> the KEEP-PRED arg of set-transient-map to t, and
> it seems both lambdas above can be used with this change:
> 
> diff --git a/lisp/repeat.el b/lisp/repeat.el
> index 84a613da0c..4be4f766ef 100644
> --- a/lisp/repeat.el
> +++ b/lisp/repeat.el
> @@ -398,7 +398,7 @@ repeat-post-hook
>             (when repeat-exit-key
>               (define-key map repeat-exit-key 'ignore))
> -            (set-transient-map map)))))))
> +            (set-transient-map map t)))))))

So there is no help message “[Repeat with o, O, ...]” displayed when use 'C-x o O’. 

Maybe we can wrap all commands in `repeat-map’ and show the help message first, then invoke the bound function?

--
Zhiwei Chen