bug#71601: 29.1; force-mode-line-update does not refresh names of tab-lines

bug#71601: 29.1; force-mode-line-update does not refresh names of tab-lines

[Al Haji-Ali]

In an `emacs -Q`, I tried the following code:

(progn
  (tab-line-mode)
  (setq-local tab-line-tab-name-function
	      (defun my/tab-name(tab &optional _)
	        (with-current-buffer tab
                  (concat (buffer-name) " " (format-time-string "%S"))))))

This works fine and I get the seconds after the buffer-name. However, I seem to have no way of updating the tab-line to cause the names to be refreshed (except to add or remove a tab).
The documentation of `force-mode-line-update` and the `:set` code of `tab-line-tab-name-function` suggest that calling `(force-mode-line-update t)` would do the trick, but on my Emacs, this does not work. Is this a bug or am I misunderstanding the documentation?

I apologize that I am unable to test this on Emacs 30.

-- Al

In GNU Emacs 29.1 (build 1, aarch64-apple-darwin22.5.0, Carbon Version
 169 AppKit 2299.6) of 2023-09-09 built on m2air.local
Windowing system distributor 'Apple Inc.', version 14.1.2
System Description:  macOS 14.1.2

Configured using:
 'configure --enable-locallisppath=/opt/homebrew/share/emacs/site-lisp
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 --mandir=/opt/homebrew/Cellar/emacs-mac/emacs-29.1-mac-10.0/share/man
 --prefix=/opt/homebrew/Cellar/emacs-mac/emacs-29.1-mac-10.0 --with-mac
 --enable-mac-app=/opt/homebrew/Cellar/emacs-mac/emacs-29.1-mac-10.0
 --with-gnutls --with-modules --with-mac-metal --with-native-compilation
 --with-tree-sitter 'CFLAGS=-I/opt/homebrew/opt/gcc/include
 -I/opt/homebrew/opt/libgccjit/include'
 'LDFLAGS=-L/opt/homebrew/lib/gcc/13 -I/opt/homebrew/opt/gcc/include
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bug#71601: 29.1; force-mode-line-update does not refresh names of tab-lines

[Juri Linkov]

> (progn
>   (tab-line-mode)
>   (setq-local tab-line-tab-name-function
> 	      (defun my/tab-name(tab &optional _)
> 	        (with-current-buffer tab
>                   (concat (buffer-name) " " (format-time-string "%S"))))))
>
> This works fine and I get the seconds after the buffer-name.  However,
> I seem to have no way of updating the tab-line to cause the names to
> be refreshed (except to add or remove a tab).
> The documentation of `force-mode-line-update` and the `:set` code of
> `tab-line-tab-name-function` suggest that calling
> `(force-mode-line-update t)` would do the trick, but on my Emacs, this
> does not work.  Is this a bug or am I misunderstanding the
> documentation?

Please try to set `tab-line-cache-key-function` to a function
that is a copy of `tab-line-cache-key-default` but where
at the end there is appended your addition of (format-time-string "%S"):

(setq tab-line-cache-key-function
      (lambda (tabs)
	(list
	 tabs
	 ;; handle buffer renames
	 (buffer-name (window-buffer))
	 ;; handle tab-line scrolling
	 (window-parameter nil 'tab-line-hscroll)
	 ;; for setting face 'tab-line-tab-current'
	 (mode-line-window-selected-p)
	 ;; for `tab-line-tab-face-modified'
	 (and (memq 'tab-line-tab-face-modified
		    tab-line-tab-face-functions)
              (buffer-file-name)
              (buffer-modified-p))
         ;; Added key:
	 (format-time-string "%S"))))

This will clear the cache every time when (format-time-string "%S")
changes, i.e. every second.

If this works, please suggest where would you expect to find this information.
Should the documentation be updated for 'tab-line-tab-name-function'?

bug#71601: 29.1; force-mode-line-update does not refresh names of tab-lines

[Al Haji-Ali]

On 17/06/2024, Juri Linkov wrote:
>
> Please try to set `tab-line-cache-key-function` to a function
> that is a copy of `tab-line-cache-key-default` but where
> at the end there is appended your addition of (format-time-string "%S"):

Indeed, the tab caching seems to be the issue. I resolved it slightly differently by clearing the cache before calling `force-mode-line-update`. 

(set-window-parameter nil 'tab-line-cache nil)
(force-mode-line-update)

whenever I want to update the tab names.

I would suggest that a solution for forcing name updates is included in the documentation for `tab-line-tab-name-format-function`, possibly defining a new function like
`tab-line-force-update`.
Also, shouldn't the cache be cleared in the `:set` code of `tab-line-tab-name-format-function`? (That's where I actually figured out that I needed to call `force-mode-line-update`).

-- Al

bug#71601: 29.1; force-mode-line-update does not refresh names of tab-lines

[Juri Linkov]

close 71601 30.0.50
thanks

>> Please try to set `tab-line-cache-key-function` to a function
>> that is a copy of `tab-line-cache-key-default` but where
>> at the end there is appended your addition of (format-time-string "%S"):
>
> Indeed, the tab caching seems to be the issue.  I resolved it slightly
> differently by clearing the cache before calling
> `force-mode-line-update`.
>
> (set-window-parameter nil 'tab-line-cache nil)
> (force-mode-line-update)
>
> whenever I want to update the tab names.
>
> I would suggest that a solution for forcing name updates is included
> in the documentation for `tab-line-tab-name-format-function`, possibly
> defining a new function like
> `tab-line-force-update`.
> Also, shouldn't the cache be cleared in the `:set` code of
> `tab-line-tab-name-format-function`?  (That's where I actually figured
> out that I needed to call `force-mode-line-update`).

Thanks for the suggestion.  So the function `tab-line-force-update`
for the `:set` code is pushed now.