[Question] Close Defx before closing/saving session with Startify

Warning: I will close the issue without the minimal init.vim and the reproduction instructions.

Problems summary

If Defx is open and I close the session with :SClose (which saves and closes the session) using Startify, then when I reopen/load the session I get the message ‘“[defx] -0” [Not Edited] --No Lines in buffer–’ and the window where Defx was at is empty of course. This is assuming that I had open Defx in a vertical split.

Also, I have the following mapping to close Nerdtree when it is open and I close another buffer (so Nerdtree is not hanging there as last Window open)

nnoremap <expr> <silent> <leader>q g:NERDTree.IsOpen() ? ':NERDTreeClose<CR>:bd<CR>' : ':bd<CR>'

Can I do something similar for Defx as well?

Expected

With NerdTree I manage to avoid this as Startify provides a option to perform a command before saving a session and NerdTree has a command to close it:

let g:startify_session_before_save = [
      \ 'silent! NERDTreeClose',
      \ ]

I would like to be able to do something similar so I don’t have to close Defx before closing the session or before deleting a buffer.

Environment Information

• defx version(SHA1):

Latest (how do I check?)

• OS: MacOS Catalina

• neovim/Vim version: Neovim v0.4.3

Provide a minimal init.vim/vimrc with less than 50 lines (Required!)

call defx#custom#option('_', {
      \ 'winwidth': 27,
      \ 'split': 'vertical',
      \ 'direction': 'topleft',
      \ 'show_ignored_files': 0,
      \ 'buffer_name': '',
      \ 'toggle': 0,
      \ 'resume': 1
      \ })

call defx#custom#column('icon', {
      \ 'directory_icon': '▸',
      \ 'opened_icon': '▾',
      \ 'root_icon': ' ',
      \ })

nnoremap <silent> ,e :Defx -toggle<CR>
nnoremap <silent> ,f :Defx -search=`expand('%:p')`<CR>

"" Startify
let g:startify_session_dir = '~/.config/nvim/sessions'
let g:startify_session_delete_buffers = 1
let g:startify_change_to_vcs_root = 1
let g:startify_session_persistence = 1
let g:startify_enable_special = 1
let g:startify_session_before_save = [
      \ 'silent! NERDTreeClose',
      \ ]

[Shougo]

Btw, is there a way to check whether Defx is open? Like with the name of the buffer, perhaps. But haven’t been able to figure it out what buffer name is given to Defx.

You should check defx filetype buffers instead of filename or check b:defx exists. You can write Vim script for it.

[Shougo]

I have added -close option for it.