VimScript - How do you get file/directory vim was called on from the command line?

Question

I am writing a little hack for vim session that will save and load sessions more conveniently - I am aiming for more project-style sessions.

When you are in directory my-proj and call vim, it should automatically open the session associated with the current directory. (This is 'almost' working so far - the problem is with getting the current directory). Saving the 'project' (i.e. a session) can be done with SaveSession

I have done this so far:

let g:session_autosave = 'yes'
let g:session_autoload = 'yes'
let g:session_default_name = getcwd()

The minor problem is, if I call vim ~/x.txt, getcwd() will not return ~/x.txt. It will return the current directory in bash (which could be almost anything). How can I get the directory that vim was called on in the command line (i.e. ~ in this case)? And if vim was opened with just vim then it should get the current working directory.

Answer 1

If you want to get the directory of the first file in :argv (the filename arguments when vim was opened): let g:session_default_name = fnamemodify(argv()[0], ':p:h'). This will fail if vim was opened with no arguments.

To fallback on getcwd() where there were no arguments:

" Returns the directory of the first file in `argv` or `cwd` if it's empty
function FindSessionDirectory() abort
  if len(argv()) > 0
    return fnamemodify(argv()[0], ':p:h')
  endif
  return getcwd()
endfunction!
let g:session_default_name = FindSessionDirectory()