How to ensure packer.startup runs before require("package")?

[steve-lorimer]

I am installing a package (nvim-mapper) using packer:

lua/plugins.lua:

packer.startup({
    function(use)

      ...

      use({
          "lazytanuki/nvim-mapper",
          config = function()
            require("nvim-mapper").setup({})
          end,
          module = "nvim-mapper",
      })

      ...

    end
})

In another file, I want to require("nvim-mapper") and call some functions therein:

lua/keybindings.lua:

local mapper = require("nvim-mapper")

local map = function(mode, lhs, rhs, opts, category, unique_identifier, description)
  mapper.map(mode, lhs, rhs, opts, category, unique_identifier, description)
end

My main init.lua file just requires the above 2 files:

init.lua:

...

require("plugins")
require("keybindings")

However, even though I've required the plugins file before the keybindings file, neovim complains on startup:

Error detected while processing /home/steve/.config/nvim/init.lua:
E5113: Error while calling lua chunk: /home/steve/.config/nvim/lua/keybindings.lua:1: module 'nvim-mapper' not found:
        no field package.preload['nvim-mapper']
        no file './nvim-mapper.lua'
        no file '/home/runner/work/neovim/neovim/.deps/usr/share/luajit-2.1.0-beta3/nvim-mapper.lua'
        no file '/usr/local/share/lua/5.1/nvim-mapper.lua'
        no file '/usr/local/share/lua/5.1/nvim-mapper/init.lua'
        no file '/home/runner/work/neovim/neovim/.deps/usr/share/lua/5.1/nvim-mapper.lua'
        no file '/home/runner/work/neovim/neovim/.deps/usr/share/lua/5.1/nvim-mapper/init.lua'
        no file './nvim-mapper.so'
        no file '/usr/local/lib/lua/5.1/nvim-mapper.so'
        no file '/home/runner/work/neovim/neovim/.deps/usr/lib/lua/5.1/nvim-mapper.so'
        no file '/usr/local/lib/lua/5.1/loadall.so'

How can I ensure that the use(... nvim-mapper) call has completed before my keybindings code runs and attempts to load it?

[wbthomason]

This is due to the order in which (Neo)vim sources files at startup.

packer, by default, outputs its loader code to plugin/packer_compiled.lua. This code includes the setup necessary for the module lazy-loader to work. The files in plugin/ are all automatically sourced during startup, but after your init.lua runs - so, your require fails.

There's a long-standing plan to move sourcing of the lazy-loaders to the very start of the startup process, but, until I have time to implement that large change, you have two options for workarounds:

1. Put your require('keybindings') in a file that runs after plugin/packer_compiled.lua, e.g. plugin/x_keybindings.lua or similar (ordering is lexicographic).
2. Use the config.compile_path configuration variable to change where packer_compiled.lua is output to a directory which is not automatically sourced by Neovim, and manually source it yourself at the top of your init file, e.g. config.compile_path = ~/.config/nvim/lua/packer_compiled.lua and require('packer_compiled') in your init file.

I hope this helps!

[steve-lorimer]

Thanks for the clarification!

Prior to your above answer, I found the section in your docs about the PackerComplete event, and created an autocmd to call a function to continue loading other modules once the plugins are loaded.

Below is the code:

require 'plugins'

_G.plugins_loaded = function()
  require 'keybindings'
end

vim.cmd [[autocmd User PackerComplete ++once lua plugins_loaded()]]

It seems to work, although is perhaps not optimal... not sure? Any comments on my so called "solution"?

Thanks again!

[wbthomason]

Huh, I'm actually kind of surprised that this approach works - PackerComplete should only fire after operations like update, sync, etc. - not on the conclusion of startup. So, really, I'm surprised that your plugins_loaded function ever runs.

[steve-lorimer]

Ah, that's good to know, thanks!

So it turns out it's working for me because I also automatically run PackerSync on startup...

    if vim.tbl_count(vim.fn.globpath(vim.fn.stdpath("data") .. "/site/pack/packer/opt", "*", 0, 1)) == 1 then
      vim.cmd("PackerSync")
    else
      vim.cmd("PackerClean")
      vim.cmd("PackerInstall")
    end

When my config is stable I would have removed the this and everything would have stoped working! 🤦