bug#32850: 27.0.50; window-swap-states doesn't swap window prev/next-buffers

[martin rudalics]

> But window-state-put has such deficiency with its undocumented
> prerequisite that a new unique window should be created manually
> before calling window-state-put to put the state into a new
> window (to not share it with other window configurations).

Maybe "to not share it with other frames" would be more precise.  What
you probably want is a facility to clone a window.  I have no idea how
to do that and which semantics to attach to a cloned window.  Always
keep in mind: Windows that have been deleted but go on "living" in
stored configurations are zombies.  And dealing with the undead can be
cumbersome ...

> This means a need in such ugly hack:
>
> ;; Create a new window
> (delete-other-windows) (split-window) (delete-window)
> ;; Put a previous state into the new window
> ;; to not share it with other window configurations
> (window-state-put previously-saved-window-state nil 'safe)
> ;; Get its window configuration
> (current-window-configuration)
>
> Please confirm is `(delete-other-windows) (split-window) (delete-window)'
> is the right idiom to create a new window to put the window state into,
> or there is a special function to create a window, that I can't find.

You can put a window state into any valid window, usually the frame's
root window.  Just that under the hood 'window-state-put' will do the
'delete-other-windows' then.

> The code above does the opposite, but it requires an ugly workaround
> for window-state-put.

Please elaborate.  In which sense does that code make a configuration
from a state?

> Like the earlier code snippet demonstrates it causes problems when
> the same window appears an arbitrary number of times in stored window
> configurations.  Thus the need to create a new window to put the state into
> (currently window-state-put itself doesn't create a new unique window).

I lost you.  Anything Lisp code can do is create a new unique window.
Lisp code cannot create a new non-unique window.

martin