Trouble using packer_plugins global

[strayer]

I'm trying to utilize the new packer_plugins global to configure stuff in lua files only for installed plugins.

For example, I only want to configure lightlines nvim-coc support if coc is actually installed:

-- statusline.lua
[...]

if packer_plugins["coc-nvim"] and packer_plugins["coc-nvim"].loaded then
  vim.fn['lightline#coc#register']()
end

My config is structured into multiple files, so my init.lua (technically a start.lua in lua/ required in init.vim right now until I can move everything over to an actual init.lua) does this:

require('plugins') -- contents as described in this projects README.md
require('statusline')

This causes nvim to throw this error when starting up:

Fehler beim Ausführen von "/Users/strayer/.config/nvim/init.vim":
Zeile 4:
E5108: Error executing lua /Users/strayer/.config/nvim/lua/statusline.lua:12: attempt to index global 'packer_plugins' (a nil value)

I'm new to lua and probably doing something very stupid here, but as far as I understand global variables should be available in another required file too. 🤷‍♂️

[wbthomason]

I think this is probably an issue regarding startup sourcing order. packer_compiled is in plugin/ (by default), which gets sourced after your init.vim. So, if you're doing these checks in your init.vim, packer_plugins doesn't exist yet. (you can see more on startup order with :help startup)

There are maybe two ways to deal with this. Option one is to move this code to a file in plugin/ that gets sourced after packer_compiled. Option two is to configure packer to put the compiled file somewhere else and manually source it in your init.vim before you run this code.

[wbthomason]

Regarding configuring packer to put the compiled file somewhere else: Is there a caveat to this except having to explicitly load the compiled vim file in init.lua/vim?

There should not be - if there is, it's a bug.

I think this may confuse a lot of people. I mainly use this to only run some configurations if a plugin is actually installed. I share my neovim config on multiple machines, but don't want to install coc on all of them, for example.

May I ask how you conditionally install plugins? It seems like keeping your configuration in a config or setup key and using either the disabled key or cond key to control installation might be a simpler/cleaner setup.

[strayer]

Before switching to packer I simply used variables and toggled some plugins based on my hostname.

" init.vim

let s:hostname = trim(system('hostname'))
let s:should_install_coc = s:hostname == 'khitomer'

" ...

" COC
if s:should_install_coc
  Plug 'neoclide/coc.nvim', {'branch': 'release'}
  " ...
endif

" ...

if s:should_install_coc
  " coc-specific functions/configurations/etc here
endif

This is essentially what you are suggesting with disabled/cond, right? I have to admit that I don't yet conditionally install coc with packer because I do the migration from vimscript to lua on the machine where all packages are installed anyway - I guess I would have used cond and check for the correct hostname(s) there.

Ideally I would like to base all configuration and such simply on the condition that the plugin is there and enabled. I think this keeps the configuration cleaner because I don't need custom conditions per package but can simply assume it needs to be configured if it is there.

[wbthomason]

If I understand what you want, I think you should be able to write something like:

local enable_coc = vim.fn.trim(vim.fn.system('hostname')) == 'khitomer'
use {'neoclide/coc.nvim', branch = 'release', disabled = not enable_coc, config = YourCocConfigFunction}

More generally, the config key is only used if a plugin is present, so whether you're determining whether to install a plugin via disabled or some other mechanism, simply putting your plugin-specific configuration in a config/setup key should handle conditionally including those functions, etc. for you.

[strayer]

Ohhh, I completely overlooked that. This is much better than what I was doing before and should cover all things I intend to do with this. And as a bonus also doesn't require me explicitly loading the compiled packer code – awesome.

Thanks a lot for pointing this out and helping me along the way!

[wbthomason]

Cool, I'm glad things are working out better!