bug#41007: 26.3; desktop-save and reloading

bug#41007: 26.3; desktop-save and reloading

[jan via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Hi,
this is trivial, feel free to ignore especially if it's just down to
my misunderstanding.

I saved my desktop using desktop-save. I could then find no way of
restoring it. I looked on the web and found a few others had the same
problem. Spent an hour browsing.
I then dug a bit more much later and found desktop-read seemed to do this.

Problem: I was looking for the obvious complement of desktop-save
which would be desktop-load or desktop-restore. Desktop-read is not
obviously named.

Other problem, and this is likely just unfamiliarity, but if you do
desktop-save it asks you where to save it. If you do desktop-read, it
doesn't ask. Docs say (desktop-read &optional DIRNAME) but that's not
exposed interactively that I can see.

Example of some confusion
<https://stackoverflow.com/questions/20438938/how-to-load-emacs-saved-desktop-configuration>

It seemed your're supposed to enable desktop-save-mode which I've
done. That's good, it works now, but having obviously named
desktop-load or desktop-restore, with an interactive prompt to ask for
the location would be good. It would also allow me to save and load
*different desktops*, *when I want* rather than at startup and just
give me the one it thinks I want.

Well, it may well allow that already, I just don't know.

Thanks

jan


In GNU Emacs 26.3 (build 1, x86_64-w64-mingw32)
 of 2019-08-29 built on CIRROCUMULUS
Repository revision: 96dd0196c28bc36779584e47fffcca433c9309cd
Windowing system distributor 'Microsoft Corp.', version 6.1.7601
Recent messages:
Warning: desktop file appears to be in use by PID 4996.
Using it may cause conflicts.  Use it anyway? (y or n) n
Desktop file in use; not loaded.
completing-read-default: Command attempted to use minibuffer while in minibuffer
s is undefined
d is undefined
Quit
Making completion list...
Auto-saving...done
Type "q" to restore previous buffer.

Configured using:
 'configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static -g3''

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY ACL GNUTLS LIBXML2 ZLIB
TOOLKIT_SCROLL_BARS THREADS LCMS2

Important settings:
  value of $LANG: ENG
  locale-coding-system: cp1252

Major mode: Apropos

Minor modes in effect:
  desktop-save-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
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emacs)

Memory information:
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bug#41007: 26.3; desktop-save and reloading

[Eli Zaretskii]

> Date: Fri, 1 May 2020 20:09:36 +0100
> From: jan via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> I saved my desktop using desktop-save. I could then find no way of
> restoring it. I looked on the web and found a few others had the same
> problem. Spent an hour browsing.
> I then dug a bit more much later and found desktop-read seemed to do this.
> 
> Problem: I was looking for the obvious complement of desktop-save
> which would be desktop-load or desktop-restore. Desktop-read is not
> obviously named.

Thanks, I added the reference to 'desktop-read' to the doc string of
'descktop-save'.

> Other problem, and this is likely just unfamiliarity, but if you do
> desktop-save it asks you where to save it. If you do desktop-read, it
> doesn't ask. Docs say (desktop-read &optional DIRNAME) but that's not
> exposed interactively that I can see.

The doc string of 'desktop-read' says:

  Interactively, with prefix arg C-u, ask for DIRNAME.

So it _is_ exposed in interactive calls.

bug#41007: 26.3; desktop-save and reloading

[Drew Adams]

> Other problem, and this is likely just unfamiliarity, but if you do
> desktop-save it asks you where to save it. If you do desktop-read, it
> doesn't ask. Docs say (desktop-read &optional DIRNAME) but that's not
> exposed interactively that I can see.

FWIW, and just in case it helps -

`desktop-read' is poorly designed, IMHO.  Or at
least some other read-a-desktop function should
be available.

desktop.el uses a desktop file to save state,
and it reads a desktop file to restore state.
But the desktop UI does not provide any function
(let alone a command) for reading a desktop file
by providing its file name.  (That's unusual for
Emacs, BTW.)

I remedied this long ago for library Bookmark+,
by adding command `bmkp-desktop-read`, which
does take a desktop file name as argument.

This is important for Bookmark+, as it lets
you easily create bookmarks to restore any
number of desktops, with their files located
anywhere (including multiple files in the same
directory).

But it should be important more generally for
Emacs, IMO.  The current (and original) design
of desktop.el assumes, in effect, that you have
at most one desktop file per directory.  And it
therefore bases its UI on the current directory,
not on an arbitrarily located desktop file.

IOW, the UI design does not really fit the
functional design, in the sense that a desktop
_file_ is what is needed.  In reality, a
desktop file can be anywhere, but nothing in
the UI suggests or supports that.

If you care about this (and I know it's not
directly related to the problem you reported)
then you can always copy the code for
`bmkp-desktop-read` and use that.  There's
really nothing in its definition that is
particularly bookmark-oriented, so it can
trivially be adapted for general use.

https://www.emacswiki.org/emacs/BookmarkPlus