Editing Working with multiple sessions

{{review}}
{{TipImported
|id=450
|previous=449
|next=451
|created=March 26, 2003
|complexity=basic
|author=Me Thinks
|version=5.7
|rating=26/8
|category1=
|category2=
}}
I usually need to work on different projects (let us call them: PROJ1 and PROJ2). These are in different directories, have different files.. etc. It would be nice if I can instruct my editor to take me back to the exact session (see :help sessions) for each of these projects - open the required files and buffers, window layout etc.

===Solution===
1. Append the following code to your [[vimrc]].

Change the variable g:PathToSessions to your desired place, if needed (make sure that this directory exists and is writable)

2. Open all/some files in a particular project (as if you are working on that) in gvim. Say I open all my PROJ1 related files.

You can split windows etc.. and make it look as if you are really working! Type

 :SetSession PROJ1

3. Quit gvim.

4. Restart gvim without any filenames at the command line.

5. You ought to get a popup-entry asking you which session to restore. Choose PROJ1.vim to see the effect.

6. Repeat with other projects.

===Note===
You don't have to :SetSession everytime you open gvim as in step 5. Only once.

If you start vim with no files at the command line, you have an option of going back to the last saved session (this is available in the gui if you choose LastSession.vim)

<pre>
au VimLeave * call VimLeave()
au VimEnter * call VimEnter()
let g:PathToSessions = $HOME . "/.vim/sessions/"

function! VimEnter()
  if argc() == 0
    " gvim started with no files
    if has("browse") == 1
      let g:SessionFileName = browse(0, "Select Session", g:PathToSessions, g:PathToSessions . "LastSession.vim")
      if g:SessionFileName != ""
        exe "source " . g:SessionFileName
      endif
    else
      " For non-gui vim
      let LoadLastSession = confirm("Restore last session?", "&Yes\n&No")
      if LoadLastSession == 1
        exe "source " . g:PathToSessions . "LastSession.vim"
      endif
    endif
  endif
endfunction

function! VimLeave()
  exe "mksession! " . g:PathToSessions . "LastSession.vim"
  if exists("g:SessionFileName") == 1
    if g:SessionFileName != ""
      exe "mksession! " . g:SessionFileName
    endif
  endif
endfunction
" A command for setting the session name
com -nargs=1 SetSession :let g:SessionFileName = g:PathToSessions . <args> . ".vim"
" .. and a command to unset it
com -nargs=0 UnsetSession :let g:SessionFileName = ""
</pre>

==Comments==
Nice tip, but I had to change the code a lot before I got it to work. Perhaps your setup (or platform) is somehow different from mine.

Anyway, here's my code. It works great for me:

<pre>
au VimLeave * call VimLeave()
au VimEnter * call VimEnter()
let g:PathToSessions = $HOME . "/.vim/sessions"

function! VimEnter()
  if argc() == 0
    " gvim started with no files
    if has("browse") == 1
      let g:SessionFileName = browse(0, "Select Session", g:PathToSessions, "/LastSession.vim")
      if g:SessionFileName != ""
        exe "source " . g:SessionFileName
      endif
    else
      " For non-gui vim
      let LoadLastSession = confirm("Restore last session?", "&Yes\n&No")
      if LoadLastSession == 1
        exe "source " . g:PathToSessions . "/LastSession.vim"
      endif
    endif
  endif
endfunction

function! VimLeave()
  exe "mksession! " . g:PathToSessions . "/LastSession.vim"
  if exists("g:SessionFileName") == 1
    if g:SessionFileName != ""
      exe "mksession! " . g:SessionFileName
    endif
  endif
endfunction

" A command for setting the session name
com! -nargs=1 SetSession :let g:SessionFileName = g:PathToSessions . "/" . <args> . ".vim"
" .. and a command to unset it
com! -nargs=0 UnsetSession :let g:SessionFileName = ""
</pre>

----
I had to had a line to VimEnter:
 exe "source ~/.vim/syntax/mysyntax.vim"
to keep my personal syntax highlighting.

Sourcing the session file seemed to switch the highlighting back to the default. Apart from that it was an excellent tip

----
One more detail: Instead of

 :SetSession PROJ1

I find I have to do

 :SetSession "PROJ1"

----
Oops.

 :SetSession "PROJ1"

is correct.

Apart from that, I don't see why the changes to the g:PathToSessions (removing the "/") and the rest of the code were needed. As has been said, maybe our setups are somehow different.. I have tested on HPUX and Windows NT.. the original script seemed to work fine..

Regarding personal syntax highlighting, normal filetype detection ought to take place, and it does for me, and the appropriate syntax file gets sourced. Again, I don't know why this doesn't work at your end..

One more issue: mksession also saves values of vim variables, like 'path' for instance, so changes in your .vimrc to these variables will get overwritten when you source the PROJ1.vim file

Maybe I'll iron these out, add some more glamour, and move it to scripts section.

----
I've edited the script a bit so that i don't have to move my hand just to use the mouse to click on the file, and make them work more consistently either GUI or non-GUI. It's just a quick hack.

<pre>
function! VimEnter()
  if argc() == 0
    let LoadLastSession = confirm("Restore last session?", "&Yes\n&No")
    if LoadLastSession == 1
      exe "source " . g:PathToSessions . "/LastSession.vim"
    else
      call LoadSessions()
    endif
  endif
endfunction

function! LoadSessions()
  let result = "List of sessions:"
  let sessionfiles = glob(g:PathToSessions . "/*.vim")
  while stridx(sessionfiles, "\n") >= 0
    let index = stridx(sessionfiles, "\n")
    let sessionfile = strpart(sessionfiles, 0, index)
    let result = result . "\n " . fnamemodify(sessionfile, ":t:r")
    let sessionfiles = strpart(sessionfiles, index + 1)
  endwhile
  let result = result . "\n " . fnamemodify(sessionfiles, ":t:r")
  let result = result . "\n" . "Please enter a session name to load (or empty to start normally):"
  let sessionname = input(result)
  if sessionname != ""
    exe "source " . g:PathToSessions . "/" . sessionname . ".vim"
  endif
endfunction
</pre>

----
===Alternative: session.vim plug-in===

The [http://peterodding.com/code/vim/session/ session.vim plug-in] ({{script|id=3150}}) extends the concepts on this page into a more full featured session manager that supports automatic session management (using a `default' session), manual session management (using named sessions) and restoring of dynamic windows created by plug-ins such as {{script|id=1658|text=NERD tree}} and {{script|id=69|text=Project}}.
@@ Line 15: / Line 15: @@
 ===Solution===
-. Append the following code to your [[vimrc]] or save the file in $HOME/.vim/plugin
+. Append the following code to your [[vimrc]].
 Change the variable g:PathToSessions to your desired place, if needed (make sure that this directory exists and is writable)
@@ Line 186: / Line 186: @@
 The [http://peterodding.com/code/vim/session/ session.vim plug-in] ({{script|id=3150}}) extends the concepts on this page into a more full featured session manager that supports automatic session management (using a `default' session), manual session management (using named sessions) and restoring of dynamic windows created by plug-ins such as {{script|id=1658|text=NERD tree}} and {{script|id=69|text=Project}}.
-----
-Here's another, [https://github.com/viespejo/dotvim/blob/master/session.vim session.vim on github].
-----
-===Alternative: gitsession.vim plug-in===
-I wrote another session plugin based on git projects and branches called [https://github.com/wting/gitsessions.vim gitsessions.vim].