Fix: Fzf-lua Zoxide Binding Stopped Working After Update

by Rajiv Sharma 57 views

Hey guys! If you're running into trouble with your Zoxide custom function binding in fzf-lua after an update, you're not alone. This article dives deep into a specific issue encountered by a user, providing a detailed solution and discussion around it. We’ll break down the problem, explore the error messages, and offer a step-by-step guide to get your configurations working smoothly again. Let's get started!

The Problem: Bug zoxide Custom Function Binding Stopped Working

The core issue revolves around a custom function, previously working, that stopped functioning correctly after an update. Specifically, the user had a function (_G.fzf_dirs) designed to switch directories using Zoxide and fzf-lua. However, after updating, they encountered an error related to upvalue references within the fn_transform function. This article will guide you through understanding and resolving this issue.

Understanding the Error Message

Before we dive into the solution, let's dissect the error message. The error encountered was:

E5108: Error executing lua: ...esn89/.local/share/nvim/lazy/fzf-lua/lua/fzf-lua/shell.lua:252: multiprocess 'fn_transform' cannot have upvalue referecnces
stack traceback:
    [C]: in function 'assert'
    ...vng/.local/share/nvim/lazy/fzf-lua/lua/fzf-lua/shell.lua:252: in function 'stringify_mt'
    ...evng/.local/share/nvim/lazy/fzf-lua/lua/fzf-lua/core.lua:159: in function 'fzf_exec'
    /Users/esn89/.config/nvim/lua/mappings.lua:20: in function </Users/esn89/.config/nvim/lua/mappings.lua:3>

This error message indicates that the fn_transform function, which is part of the fzf-lua configuration, cannot have upvalue references in a multiprocess context. Upvalues are essentially variables from the enclosing scope that the function uses. In simpler terms, the function is trying to use something from outside its immediate environment, which is causing a problem in the new update.

Initial Configuration

To provide context, here’s the initial Lua configuration that triggered the error:

-- function for switching dirs
_G.fzf_dirs = function(opts)
    local fzf_lua = require('fzf-lua')
    opts = opts or {}
    opts.prompt = ' 📁 '
    opts.fn_transform = function(x)
        return fzf_lua.utils.ansi_codes.cyan(x)
    end
    opts.preview = 'eza --color=always -T -L 3 {}'
    opts.actions = {
        ['default'] = function(selected)
            if selected[1] == nil then
                vim.notify_once('derp')
                return
            end
            vim.cmd('cd ' .. selected[1])
        end,
    }
    fzf_lua.fzf_exec('zoxide query -l', opts)
end

-- map our provider to a user command ':Directories'
vim.cmd([[command! -nargs=* Zox lua _G.fzf_dirs()]])

vim.keymap.set('n', '<Leader>z', _G.fzf_dirs, { noremap = true, silent = true })

This configuration defines a global function _G.fzf_dirs that integrates Zoxide with fzf-lua to allow directory switching. The fn_transform function is used to apply ANSI color codes to the directory names, enhancing their appearance in the fzf-lua interface.

The Solution: Refactoring the fn_transform Function

The key to resolving this issue is to refactor the fn_transform function to avoid upvalue references. This typically involves moving the necessary functionality directly into the function's scope or using a different approach that doesn't rely on external variables. Let's explore the solution provided by the user and how it addresses the problem.

The user refactored the code by making fzf_lua a local variable within the function and directly accessing fzf_lua.utils.ansi_codes.cyan within the fn_transform function. Here’s the corrected code:

_G.fzf_dirs = function(opts)
    local fzf_lua = require('fzf-lua') -- Make fzf_lua local
    opts = opts or {}
    opts.prompt = ' 📁 '
    local ansi_codes = fzf_lua.utils.ansi_codes -- Store ansi_codes locally
    opts.fn_transform = function(x) -- Define fn_transform with no upvalue
        return ansi_codes.cyan(x)
    end
    opts.preview = 'eza --color=always -T -L 3 {}'
    opts.actions = {
        ['default'] = function(selected)
            if selected[1] == nil then
                vim.notify_once('derp')
                return
            end
            vim.cmd('cd ' .. selected[1])
        end,
    }
    fzf_lua.fzf_exec('zoxide query -l', opts)
end

vim.cmd([[command! -nargs=* Zox lua _G.fzf_dirs()]])

vim.keymap.set('n', '<Leader>z', _G.fzf_dirs, { noremap = true, silent = true })

Explanation of the Fix

  1. Localizing fzf_lua: The fzf_lua variable is now declared locally within the _G.fzf_dirs function. This ensures that the function has its own context and doesn't rely on a global scope.
  2. Storing ansi_codes Locally: The ansi_codes table is extracted from fzf_lua.utils and stored in a local variable. This is the critical step, by caching ansi_codes before defining fn_transform we remove the upvalue reference.
  3. fn_transform Without Upvalues: The fn_transform function now directly uses the local ansi_codes variable. This eliminates the upvalue reference, resolving the error. By referencing ansi_codes directly within the scope of fn_transform, the function operates independently, making it safe for multiprocessing.

Why This Works

By removing the upvalue reference, the fn_transform function becomes self-contained. This is crucial because fzf-lua might execute this function in a separate process, where access to upvalues (variables from the enclosing scope) is restricted. The corrected code ensures that the function has everything it needs within its own scope, allowing it to run smoothly in any context.

Additional Tips and Considerations

Keeping Dependencies Local

Whenever you're working with functions that might be executed in a separate process or context, it's a good practice to keep dependencies local. This means ensuring that the function has direct access to the variables and modules it needs without relying on external scopes.

Testing Your Configuration

After making changes to your configuration, always test thoroughly to ensure everything is working as expected. You can use :lua print(vim.inspect(your_variable)) to inspect variables and ensure they hold the correct values.

Debugging with Logs

If you encounter issues, use vim.notify or print statements to log relevant information. This can help you trace the flow of execution and identify the source of the problem.

Understanding fzf-lua Internals

Familiarizing yourself with the internals of fzf-lua can provide a deeper understanding of how it works and help you troubleshoot issues more effectively. Review the fzf-lua documentation and explore the source code to gain insights into its architecture and functionality.

Other Possible Solutions

While the above solution directly addresses the upvalue issue, there are alternative approaches you might consider:

  1. Using vim.fn: If the functionality you need can be achieved using Vimscript functions, consider using vim.fn to call those functions from Lua. This can sometimes simplify the code and avoid issues with upvalues.
  2. External Scripts: For more complex transformations, you might consider using external scripts. This involves writing a script in a language like Python or Bash and calling it from your Lua function. This can help isolate the logic and avoid issues with Neovim's Lua environment.

Conclusion

Encountering errors after updates can be frustrating, but understanding the root cause and applying the correct solution can turn these challenges into learning opportunities. In this article, we’ve walked through a specific issue with fzf-lua and Zoxide, providing a detailed solution and explaining the underlying principles. By refactoring the fn_transform function to avoid upvalue references, the user was able to restore their custom function binding and continue enjoying the benefits of fzf-lua. Remember, keeping dependencies local and testing your configuration are key practices for smooth sailing in Neovim customization. Happy coding, guys!