Disabling nvim autoformat on a per-repo basis

I’m a huge fan of Folke’s Neovim distribution lazyvim. It has replaced my own custom lua config, and reduced the time I’m spending tweaking my config by a lot.

One nice thing is it enables format on save by default, which is actually what I want for almost all things. However in some repos I contribute to they frown upon this behavior, so I have to constantly remember to turn it off with <space>uf or suffer review comments about excessive white-space fixes :)

That kinda works, but I sometimes forget, and have to undo after save and turn it off. However now I have a better solution:

vim.api.nvim_create_autocmd({ "BufEnter" }, {
  pattern = vim.fn.expand("~") .. "/Source/{nimdow,nixpkgs}/*",
  callback = function()
    vim.b.autoformat = false
  end,
})

Add this to autocmd.lua and whenever you enter a buffer inside nimdow or nixpkgs it automatically turns off autoformat. Note how I’m expanding ~ in this scenario rather than putting in /home/marcus to ensure it works on MacOs as well as Linux.