Disable colorcolumn on BufLeave

Question

I would like to disable the colorcolumn in a buffer when switching to a different buffer. I try to perform this with a autocommand using the BufLeave Event.

In Neovim I use the following

local set_colorcolumn = function()
    local buf = vim.api.nvim_get_current_buf()
    vim.notify("BufEnter " .. tostring(buf))
    vim.opt_local.colorcolumn = "80"
end
local unset_colorcolumn = function()
    local buf = vim.api.nvim_get_current_buf()
    vim.notify("BufLeave " .. tostring(buf))
    vim.opt_local.colorcolumn = "0"
end

local colorcolumn_group = vim.api.nvim_create_augroup("CursorColumn", { clear = true })

vim.api.nvim_create_autocmd(
    { "BufEnter" },
    { pattern = "*.lua", group = colorcolumn_group, callback = set_colorcolumn }
)

vim.api.nvim_create_autocmd(
    { "BufLeave" },
    { pattern = "*.lua", group = colorcolumn_group, callback = unset_colorcolumn }
)

In Vim it would be

augroup colcol
    au BufEnter *.lua :setlocal colorcolumn=80
    au BufLeave *.lua :set colorcolumn=0
augroup end

In both cases the colorcolumn persists when switching buffers. I also tried to call redraw in the neovim case, with no success.

Can anybody explain why I'm experiencing this behavior? Is this to be expected.

Answer 1

I believe there is a miss understanding about the pattern. The code only make the modification when you switch to a lua file.

I would try:

local set_colorcolumn = function()
    local buf = vim.api.nvim_get_current_buf()
    vim.notify("BufEnter " .. tostring(buf))
    vim.opt_local.colorcolumn = "80"
end
local unset_colorcolumn = function()
    local buf = vim.api.nvim_get_current_buf()
    vim.notify("BufLeave " .. tostring(buf))
    vim.opt_local.colorcolumn = "0"
end

local colorcolumn_group = vim.api.nvim_create_augroup("CursorColumn", { clear = true })

vim.api.nvim_create_autocmd(
    { "BufEnter" },
    { pattern = "*", group = colorcolumn_group, callback = set_colorcolumn }
)

vim.api.nvim_create_autocmd(
    { "BufLeave" },
    { pattern = "*", group = colorcolumn_group, callback = unset_colorcolumn }
)

Answer 2

If you want the colorcolumn to follow the cursor, you can do the following:

augroup colcol
  au!
  au VimEnter,WinEnter,BufWinEnter *.lua :setlocal colorcolumn=80
  au WinLeave *.lua :set colorcolumn=0
augroup end

I prefer to write autocommands for Neovim using vim.cmd, then it would look like:

vim.cmd([[
  augroup colcol
    au!
    au VimEnter,WinEnter,BufWinEnter *.lua :setlocal colorcolumn=80
    au WinLeave *.lua :set colorcolumn=0
  augroup end
]])