Force Vim's mksession to use relative paths?

Question

I'm trying to save my session in Vim with relative paths to open files. With cur_dir in sessionoptions, the paths to files will be relative wrt. current directory, but the session file contains cd /path/to/base/directory command:

...
cd /path/to/base
badd +0 relpath1/file
badd +0 relpath2/file
...

If I leave curdir out of sessionoptions, the cd command disappears, but file paths will be absolute:

badd +0 /path/to/base/relpath1/file
badd +0 /path/to/base/relpath2/file

Is there a way to have only relative paths wrt. to whatever was the current directory when the session was created -- without plugins or writing scripts? So that the session file would only have:

badd +0 relpath1/file
badd +0 relpath2/file

My ultimate goal is to have a session file that I can copy around, e.g. from SVN checkout to another.

Answer 1

You can't do that without setting up a wrapper function for it, AFAIK.

E.g. something like:

function! MakeSession()
  let b:sessiondir = getcwd()
  let b:filename = b:sessiondir . '/session.vim'
  exe "mksession! " . b:filename
  exe "edit! " . b:filename
  exe "g:^cd :d"
  exe "x" 
endfunction