Integrate with desktop-mode

[mattiasb]

Hi!

I just wrote a little snippet (below) to my init.el that lets me restore the currently opened buffers with the help of the desktop.el module after a restart. Would you be interested in a PR?

(defun my/restart-emacs ()
  "Restart Emacs with desktop restored."
  (interactive)
  (let ((desktop-dir (getenv "XDG_RUNTIME_DIR")))
    (desktop-save desktop-dir)
    (restart-emacs (list "--eval"
                         (format "(progn (desktop-read \"%s\") (desktop-remove))"
                                 desktop-dir)))))

[iqbalansari]

Hi,

Thanks a lot for the contribution. This looks like a useful addition and I am interested in adding this functionality, however I think it will need some more polish before we add it. My main concern is that this package's use of desktop-mode should not interfere with that of the user. Ideally the above should be disabled if the user is already using desktop mode.

Also how do suggest this functionality should work. I think there are two ways to support this

1) It can be a customizable variable that the user can set to t if she wants the buffers to be automatically restored after restart 2) It can be a separate command that the user can call if she wants the buffers to be automatically restored after restart 3) Obviously it can be a combination of both

I am leaning towards the third option since that seems to provide the most flexibility. Thoughts?

Thanks

[mattiasb]

So the default path for desktop-mode is somewhere under ~/.emacs.d.

What the above code does is put it under the user's runtime directory (mounted as tmpfs on Linux) and delete it directly after the restore. So I kind of thought about conflicts already.

I'm thinking a polished up version would make the path to the temporary desktop configurable but default to something like (concat (getenv "XDG_RUNTIME_DIR") "/restart-emacs/"):

• Adding the "/restart-emacs/" suffix makes sure that we don't even conflict with the unlikely scenario that someone's already saving their desktops inside XDG_RUNTIME_DIR.
• Making the path configurable seems reasonable since someone might be running this on OSX or some very oldschool-style linux distribution.

Regarding how to expose it I'm not really sure. I'd go with option 2 personally.

[iqbalansari]

Other option might be to use the function make-temp-file to create a temporary file, and store the desktop-mode configuration there, this would work on all platforms that Emacs supports the make-temp-file functionality irrespective of the whether XDG_RUNTIME_DIR is set or no.

There may be multiple issues with desktop mode, I know atleast one, which encountered while trying to use to restore frames after daemon restarts.

It sets the variable desktop-dirname whenever it reads from a desktop file, similarly desktop-remove sets the desktop-dirname to nil. Now this is not an issue if your configuration does not use desktop-save-mode, but if you are using it, then it prompts whether you want to save the buffers and location of the desktop file, this is a bit annoying because in the usual flow desktop mode works transparently without any prompts.

Perhaps we can workaround that issues by modifying you code to the follow (warning completely untested)

(defun my/restart-emacs ()
  "Restart Emacs with desktop restored."
  (interactive)
  (let ((desktop-dir temporary-file-directory)
        desktop-dirname)
    (desktop-save desktop-dir)
    (restart-emacs (list "--eval"
                         (prin1-to-string `(let (desktop-dirname)
                                             (desktop-read ,desktop-dir)
                                             (desktop-remove)))))))

We can keep this a separate command for now, also we should make sure this new command behaves similar to the current restart-emacs command (single prefix argument starts Emacs with --debug-init, two prefix arguments start Emacs with -Q and three prefix arguments read additional flags from the user).

Feel free to open a pull request with above changes.

Thanks

[mattiasb]

This all makes sense. Hopefully I'll get on this tomorrow or later this week.

[alagalah]

Regardless of how its implemented, it would make this great plugin extremely useful if you could "restart-emacs" and pickup where you left off.

[iqbalansari]

Hi @alagalah, I had tried using desktop-mode on feature/daemon branch. However I was not satisfied with the code let me see I could clean it up a bit and merge to master. For now you can just enable desktop-mode and your buffers and frames would be restored on across restarts. Does that work for you?

[iqbalansari]

Hi @mattiasb, @alagalah

I have pushed initial support for this on the master branch, right now it is disabled by default to enable it put something like the below to your init file

(setq restart-emacs-restore-frames t)

[mattiasb]

Awesomesauce! Sorry for not getting back, life kind of got in the way.

[iqbalansari]

No worries @mattiasb, I can understand :smile: