Can I retain and restore all the GUI windows and its files on launch on Vim?

Question

I'm currently using the session saving to restore the state when the app (MacVim) is closed.

nnoremap <leader>q :mksession! ~/.vim/Session.vim<CR>:wqa<CR>
nnoremap <leader>www :mksession! ~/.vim/Session.vim<CR>:qa!<CR>

function! RestoreSession()
   if argc() == 0 "vim called without arguments
        execute (has("gui_running") ? "" : "silent!") 'source ~/.vim/Session.vim'
   end
endfunction
autocmd VimEnter * call RestoreSession()

However, this only works for a single GUI window. When I trigger the shortcut, it closes the current window. After all the windows are closed in the same way and then I open the app again, only the last closed GUI window is restored.

Is there any way to close all the GUI windows simultaneously and restore all of them on the next launch?

Answer 1

As I mentioned in my comments a session is associated with a single invocation of Vim so you can't do exactly what you're hoping to do. But I also mentioned something might be possible using shell scripts and Vim's "clientserver" functionality. I decided to chase that down...primarily for my own edification but since it works I figured I'd share it. (Your version of Vim must be compiled with +clientserver. Look at the output of :version.)

These are rudimentary scripts. My goal is just to demonstrate the concept rather than build production-grade stuff.

save_vim_sessions.sh

#!/bin/bash  

# For each instance of Vim save the session in a common directory,
# save the files, and then quit Vim. You can run this from one of
# the Vim instances if you like, perhaps using a key mapping.

SESSDIR=/tmp/vimsess
if [[ -d $SESSDIR ]]; then
    rm "$SESSDIR"/* 2> /dev/null
else
    mkdir -p "$SESSDIR"
    chmod 0777 "$SESSDIR"
fi

for server in $(vim --serverlist); do
    vim --servername "$server" \
        --remote-send ':<c-u>mksession! $TMP/vimsess/%:t<cr>' \
        --remote-send ':wqa<cr>'
done

For the most part the --remote-send parameters are self explanatory with the possible exception of <c-u> and %:t. <c-u> sends Ctrl-U which clears the Vim command line in case some text was already present. % represents the file path/name loaded in the current buffer. :t is a modifier that strips off the path and leaves just the name. For example, if you're editing /foo/bar.txt the session will be saved in /tmp/vimsess/bar.txt. It's a quick and dirty way to choose a relatively unique name for the session file. (Remember this isn't production-grade.)

launch_vim_sessions.sh

#!/bin/bash  

# Launch a vim session for each file in the common directory. 
# The end result is to exactly restore everything closed by 
# the other script.

SESSDIR=/tmp/vimsess
if [[ ! -d $SESSDIR ]]; then
    echo "Directory $SESSDIR not found"
    exit 1
fi

for sess in "$SESSDIR"/*; do
    vim -S "$sess" &
done

This assumes that $TMP in Vim has value /tmp. Update that and the directory in SESSDIR as needed to match your own preferences and/or system.

I'm using command vim here but that could just as well be gvim...I tested it with GUI windows as opposed to terminal Vim (the question is about GUI vim).

That's it.