RE: calling desktop-read interactively

[Drew Adams <drew.adams@oracle.com>]

> > So, if we were to support multiple filenames, it surely wouldn't just be
> > changing desktop-read to ask for the file name, but fully support multiple
> > desktop files everywhere.
> 
> Indeed.
> 
> > That's a feature nobody's asked for before, I think.

See below.

> It just seems so weird to only be able to specify the file indirectly via
> the dir in which it lives.

Seems weird indeed.  I've never understood the why of
that design.

> It works OK if you have different "desktops"
> for different projects placed in different subdirectories, but if you
> have different "desktops" for different kinds of sessions (e.g. one for
> email, one for programming, ...) then having to place the desktops in
> different subdirectories feels awkward (especially since there isn't
> necessarily many more files to put in those directories).
> 
> Being *able* to specify a directory is great.  Being limited to that is odd.

Sincere apologies for jumping in here, especially without
reading all of the thread.

FWIW, I have, I'm pretty sure, asked for exactly that feature.
Or at least I've mentioned that it is, IMO, a failing that the
design of desktop.el is _only_ directory-oriented, assuming
that you want/need at most one desktop file per directory.
(Why was such an assumption made?  I've never understood it.)

Long ago I implemented this feature - ability to read a
desktop file anywhere, i.e., by file name, in the Bookmark+
code.  There, users can have any number of desktop files, in
any directories.  They can create bookmarks for them, and so
restore desktops by jumping to bookmarks.

Function `bmkp-desktop-read' reads a desktop file.  Maybe it
will help, e.g. by saving a little time, to take a look at
that code.  It's in file bookmark+-1.el, here:

https://www.emacswiki.org/emacs/download/bookmark%2b-1.el

Anyway, here is that code:

;; Derived from code in `desktop-read'.
(defun bmkp-desktop-read (file)
  "Load desktop-file FILE, then run `desktop-after-read-hook'.
Return t if FILE was loaded, nil otherwise."
  (interactive)
  (unless (file-name-absolute-p file) ; Should never happen.
    (setq file  (expand-file-name file bmkp-desktop-default-directory)))
  (when (file-directory-p file) (error "`%s' is a directory, not a file" file))
  (setq desktop-dirname  (file-name-directory file))
  (if (not (file-readable-p file))
      nil                               ; Return nil, meaning not loaded.
    (let ((desktop-restore-eager      t) ; Don't bother with lazy restore.
          (desktop-first-buffer       nil)
          (desktop-buffer-ok-count    0)
          (desktop-buffer-fail-count  0)
          (desktop-save               nil)) ; Prevent desktop saving during eval of desktop buffer.
      (when (fboundp 'desktop-lazy-abort) (desktop-lazy-abort)) ; Emacs 22+.
      (load file t t t)
      (when (boundp 'desktop-file-modtime) ; Emacs 22+
        (setq desktop-file-modtime  (nth 5 (file-attributes file))))
      ;; `desktop-create-buffer' puts buffers at end of the buffer list.
      ;; We want buffers existing prior to evaluating the desktop (and not reused) to be placed
      ;; at the end of the buffer list, so we move them here.
      (mapc 'bury-buffer (nreverse (cdr (memq desktop-first-buffer (nreverse (buffer-list))))))
      (bmkp--pop-to-buffer-same-window (car (buffer-list)))
      (run-hooks 'desktop-delay-hook)
      (setq desktop-delay-hook  ())
      (run-hooks 'desktop-after-read-hook)
      (when (boundp 'desktop-buffer-ok-count) ; Emacs 22+
        (message "Desktop: %d buffer%s restored%s%s." desktop-buffer-ok-count
                 (if (= 1 desktop-buffer-ok-count) "" "s")
                 (if (< 0 desktop-buffer-fail-count)
                     (format ", %d failed to restore" desktop-buffer-fail-count)
                   "")
                 (if (and (boundp 'desktop-buffer-args-list)  desktop-buffer-args-list)
                     (format ", %d to be restored lazily" (length desktop-buffer-args-list))
                   "")))
      t)))

If something that offers the same thing becomes available
in vanilla Emacs then, at least for the most recent
releases, the Bookmark+ code can just make use of the
vanilla function.  If not, that's OK too.  HTH.