sk1u's Blog

Pyenv, Neovim, Virtualenv, Homebrew, and a few gotchas

16 Apr 2018

[ python  ]

Right, since we are gonna talk about this, I just have to do it:

exiting vim joke

Now that we’ve got at least one of the jokes about exiting Vim out of our system, let’s get started.

For my dev workflow and IDE, I’ve recently decided to move from the excellent Vim, and into the magical world of NeoVim, which is essentially Vim on steroids.

No, but seriously, NeoVim has a few features that are really interesting, but the real reason for moving is that, as a Python dev, I need to be able to look at source code and definitions very often, while hacking on my code. The wonderful jedi-vim plugin normally allows me to do just that, when it comes to my local project. But because I am using virtual environments extensively in my work, such as with virtualenv and/or pyenv, I have a problem on my hands:

jedi-vim is unfortunately unaware of virtual environments.

So if I for example,

setup a virtual environments in my project dir as such:

$ virtualenv -m python 3 venv

Activate the environment:

$ source venv/bin/activate

and then install Django:

$ pip install django

Initialise a django app with:

$ django-admin startproject mysite

Open the urls file:

$ vim mysite/urls.py

Placing the cursor on an object we are importing, such as url, and running the jedi-vim goto definition shortcut (mine is ,d):

from django.conf.urls import url
from django.contrib import admin

Returns the following error:

jedi-vim: Couldn't find any definitions for this.

Which sucks.

Spent a good amount of time googling, asking around, playing with different plugins, but nope, no joy. The internet was suggesting three things:

  1. suck it up, cause similar issues were not tackled yet.
  2. tackle the issue myself, for which I feel I am not well versed enough (yet).
  3. Move to NeoVim plus Pyenv and jedi-vim, where things magically work.

So here I am with my brand new NeoVim setup.

I need to watch Raiders again.

Of course I had to go through a few gotchas to get this to work, which I will share here for all those out there hacking around with this.

Installing PyEnv

The first thing I did was to ditch virtualenv and use Pyenv instead. I used homebrew to do that.

$ brew update
$ brew install pyenv
$ brew install pyenv-virtualenv

We still need to complete the install by adding a few environment variables to our shell profiles. So depending on our preferred shell, we use ~/.bash_profile , or ~/.zshrc or whatever else:

$ echo 'export PYENV_ROOT="$HOME/.pyenv"' >> <profile_file>
$ echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> <profile_file>
$ echo -e 'if command -v pyenv 1>/dev/null 2>&1; then\n  eval "$(pyenv init -)"\nfi' >> <profile_file>

(more info on PyEnv Github)

We can then initialize some environments and play around:

$ pyenv install 3.6.5
$ pyenv install 2.7.14
$ pyenv virtualenv 2.7.14 my_p2_project
$ pyenv virtualenv 3.6.5 my_p3_project
$ pyenv activate my_p3_project
$ pyenv versions
$ pyenv deactivate

Installing NeoVim and jedi-vim

For NeoVim, I used, you guess it, Homebrew:

$ brew install neovim

At which point, we can run it with:

$ nvim

I then proceeded to install a bunch of plugins for my Python stuff. I took a great deal of inspiration from Fisa’s NeoVim configuration for that, but for the sake of this guide, we can simply install the jedi-vim plugin by adding the following to our ~/.config/nvim/init.vim :

call plug#begin('~/.config/nvim/plugged')
Plug 'davidhalter/jedi-vim
call plug#end()

We can then reopen nvim and run a :PlugInstall

Now for our gotcha part

For being able to use Python 2/3 plugins,we will need the neovim Python module, with:

pip install neovim

But this would mean that we’d have to install the neovim plugin in all the virtual environments we create. To get around this, we need to create 1-2 virtual environments just for neovim, and add a line in our init.vim that will tell nvim to look into those envs for its plugin. We do the following:

pyenv virtualenv 2.7.14 neovim2
pyenv virtualenv 3.6.5 neovim3

pyenv activate neovim2
pip install neovim
pyenv which python  # Note the path

pyenv activate neovim3
pip install neovim
pyenv which python  # Note the path

We will need to add also the following to our ~/.config/nvim/init.vim:

let g:python_host_prog = '/path/to/neovim2/bin/python'
let g:python3_host_prog = '/path/to/neovim3/bin/python'

Run a health check in nvim to make sure all is ok:

:CheckHealth

Once this is done, we are all set! Time to write some Python :)

funstuff


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