Support XDG directory specification?

[DianeOfTheMoon]

Given the fact that Neovim uses the xdg directory specification should OmniSharp-vim also support it, if it's detected? I think where the server is installed is about the only item that would be updated.

[nickspoons]

Perhaps ... the reason that OmniSharp-vim installs OmniSharp-roslyn under ~/.omnisharp is because OmniSharp-roslyn already uses that directory, that's where ~/.omnisharp/omnisharp.json is.

Related: OmniSharp/omnisharp-roslyn#953

[nickspoons]

@DianeOfTheMoon I just noticed OmniSharp/omnisharp-roslyn#1317 which checks for an $OMNISHARPHOME environment variable for the omnisharp.json file. Using that would be pretty simple, but I suppose we could check for any of $OMNISHARPHOME, $XDG_DATA_HOME, ~/.local/share and use any of those if they exist - does that sound reasonable?

Were you considering making a PR? Note that this involves both installing the server and starting it.

[DianeOfTheMoon]

Yeah, I'd put up a PR, just wanted to get your read before I did. $XDG_DATA_HOME, then $OMNISHARPHOME, then default to $HOME/.omnisharp? I'll try and consolidate the path construction in the process...sound good?

[DianeOfTheMoon]

@nickspoons Since I've never really done anything with Vimscript, does this look right to you? It should not break existing installs, but prefer XDG for neovim installations:

if exists('g:OmniSharp_server_path')
  let g:OmniSharp_server_home = fnamemodify(g:OmniSharp_server_path, ':p:h')
else
  if exists('$OMNISHARPHOME')
    let g:OmniSharp_server_home = $OMNISHARPHOME
  endif
endif

if !exists('g:OmniSharp_server_home')
  " We should start by seeing if someone already has an install or basic
  " config
  let dir_separator = fnamemodify('.', ':p')[-1 :]
  let root_path = [expand('$HOME'), '.omnisharp']
  let root_dir = join(root_path, dir_separator)
  let settings_file = join(root_path + ['omnisharp.json'], dir_separator)

  if filereadable(settings_file) || isdirectory(root_dir) || !has('nvim')
    let g:OmniSharp_server_home = root_dir
  else
    " Neovim uses the XDG directory specification, so we should, too
    if has('win32')
      let data_home_default = expand('%APPDATALOCAL%')
    else
      let data_home_default = join([expand('$HOME'), '.local', 'share'], dir_separator)
    endif
    let data_home = exists('$XDG_DATA_HOME') ? $XDG_DATA_HOME : data_home_default
    let g:OmniSharp_server_home = join([data_home, 'omnisharp'], dir_separator)
  endif
endif

Sorry to be a bit gun shy, but want to validate this before updating anything else and I don't know if I'm over complicating it.

[nickspoons]

@DianeOfTheMoon looks good!

1. I don't think we should treat Vim and Neovim differently.
2. I believe APPDATALOCAL should be LOCALAPPDATA, and in my Windows 10 gvim echo expand('%LOCALAPPDATA%') doesn't output anything, but echo expand('$LOCALAPPDATA') does.
3. For the sake of consistency, lets always wrap environment variables with expand() (there are unwrapped $OMNISHARPHOME and XDG_DATA_HOME).

If you want to get something up that's easier to collaborate on, just bang up a PR with "WIP" in the title - I won't merge it before you give me the go-ahead. That way it's easier to comment on the code and see it in context (I don't have a problem with doing it here, just a suggestion because the PR system works well).

[nickspoons]

Closed by #513