Writing a Neovim plugin

Introduction

I have been using Neovim for a while now, and I find it to be a great tool. However, I have never had the opportunity to write a plugin for it. Recently, I came across Charmbracelet's new app called "Freeze" which I liked, the app allows you to generate images of code snippits. This inspired me to integrate it into Neovim.

The Idea

The goal was to allow the user to select a range of text and then generate an image from that. If the user did not select an area of text then it would use the entire file.

The Implementation

To do this I created a set of allowed options the user could set when calling the setup() function for the plugin. The options would be identical to the arguments the cli command would take except in snake case. We could then use this data to generate a CLI command and call it with vim.fn.system(), and we could get the output and use that to give the user a log of what happened with vim.notify().

I also wanted to ensure that the user's options would actually work, so I created a function that would check the options and ensure that they were correct. This was done by checking the options against a list of allowed options and ensuring they were the correct type. At this point I realized I was enforcing the user to use the command freeze, but I did not account for use cases other than mine, so this was added as an option.

The struggle

Neovim's documentation when it comes to old and new versions and what APIs are available is not the best. I found myself having to look at the source code of the plugin manager I was using to see what was available. Thankfully @comfysage managed to get to the bottom of it. The following snippet shows how we handle arrays and lists differently depending on Neovim versions.

local function is_array(...)
  if vim.fn.has("nvim-0.10") == 1 then
    return vim.tbl_isarray(...)
  else
    return vim.tbl_islist(...)
  end
end

The outcome

The plugin was a success, and I was able to generate images from code snippets. I was also able to learn a lot about how to write a Neovim plugin and how to use the Neovim API. I was also able to learn a lot about how to use Vimscript and how to use the command line from within Neovim. This was a great experience, and I am thankful for it. See an example of the plugin below.

The plugin is available on GitHub under isabelroses/charm-freeze.nvim.