#+TITLE:  Configuring Python in Emacs
#+AUTHOR: Howard X. Abrams
#+DATE:   2021-11-16
#+FILETAGS: :emacs:

A literate programming file for configuring Python.

#+BEGIN_SRC emacs-lisp :exports none
  ;;; ha-programming-python.el --- A literate programming file for configuring Python. -*- lexical-binding: t; -*-
  ;;
  ;; Copyright (C) 2021 Howard X. Abrams
  ;;
  ;; Author: Howard X. Abrams <http://gitlab.com/howardabrams>
  ;; Maintainer: Howard X. Abrams
  ;; Created: November 16, 2021
  ;;
  ;; This file is not part of GNU Emacs.
  ;;
  ;; *NB:* Do not edit this file. Instead, edit the original literate file at:
  ;;            /Users/howard.abrams/other/hamacs/ha-programming-python.org
  ;;       And tangle the file to recreate this one.
  ;;
  ;;; Code:
  #+END_SRC
* Introduction
The critical part of Python integration with Emacs is running LSP in Python using [[file:ha-programming.org::*direnv][direnv]]. And the only question to ask is if the Python we run it in Docker or in a virtual environment.
** Virtual Environment
For a local virtual machine, simply put the following in your =.envrc= file:
#+begin_src conf
layout_python3
#+end_src
That is pretty slick and simple.

The old way, that we still use if you need a particular version of Python, is to install [[https://github.com/pyenv/pyenv][pyenv]] globally:
#+BEGIN_SRC sh
pip install pyenv
#+END_SRC

And have this in your =.envrc= file:
#+begin_src conf
use python 3.7.1
#+end_src

Also, you need the following in your =~/.config/direnv/direnvrc= file (which I have):
#+begin_src shell
use_python() {
  local python_root=$(pyenv root)/versions/$1
  load_prefix "$python_root"
  if [[ -x "$python_root/bin/python" ]]; then
    layout python "$python_root/bin/python"
  else
    echo "Error: $python_root/bin/python can't be executed."
    exit
  fi
}
#+end_src
** Docker Environment
Docker really allows you to isolate your project's environment. The downside is that you are using Docker and probably a bloated container. On my work laptop, a Mac, this creates a behemoth virtual machine that immediately spins the fans like a wind tunnel.

But, but... think of the dependencies!

Enough of the rant (I go back and forth), after getting Docker installed and running (ooo Podman ... shiny), and you've created a =Dockerfile= for your project, let's install [[https://github.com/snbuback/container-env][container-env]].

Your project's =.envrc= file would contain something like:
#+begin_src shell
CONTAINER_NAME=my-docker-container
CONTAINER_WRAPPERS=(python3 pip3 yamllint)
CONTAINER_EXTRA_ARGS="--env SOME_ENV_VAR=${SOME_ENV_VAR}"

container_layout
#+end_src
** Python Dependencies
Whew. Each Python project's =requirements-dev.txt= file would reference the [[https://pypi.org/project/python-lsp-server/][python-lsp-server]] (not the /unmaintained/ =python-language-server=):
#+begin_src conf
python-lsp-server[all]
#+end_src

*Note:* This does mean, you would have a =tox.ini= with this line:
#+BEGIN_SRC conf
  [tox]
  minversion = 1.6
  skipsdist = True
  envlist = linters
  ignore_basepython_conflict = True

  [testenv]
  basepython = python3
  install_command = pip install {opts} {packages}
  deps = -r{toxinidir}/test-requirements.txt
  commands = stestr run {posargs}
             stestr slowest
  # ...
#+END_SRC
*** Using Jedi Instead
Do we want to use the Jedi version of LSP? Not sure what it buys us.
#+BEGIN_SRC emacs-lisp :tangle no
(use-package lsp-jedi
  :config
  (with-eval-after-load "lsp-mode"
    (add-to-list 'lsp-disabled-clients 'pyls)
    (add-to-list 'lsp-enabled-clients 'jedi)))
#+END_SRC
* LSP Integration of Python
Now that the [[file:ha-programming.org::*Language Server Protocol (LSP) Integration][LSP Integration]] is complete, we can stitch the two projects together:

#+BEGIN_SRC emacs-lisp
  (use-package lsp-mode
    :hook ((python-mode . lsp)))
#+END_SRC
And we're done.
* Technical Artifacts                                :noexport:
Let's =provide= a name so we can =require= this file:

#+BEGIN_SRC emacs-lisp :exports none
  (provide 'ha-programming-python)
  ;;; ha-programming-python.el ends here
  #+END_SRC

#+DESCRIPTION: A literate programming file for configuring Python.

#+PROPERTY:    header-args:sh :tangle no
#+PROPERTY:    header-args:emacs-lisp  :tangle yes
#+PROPERTY:    header-args    :results none :eval no-export :comments no mkdirp yes

#+OPTIONS:     num:nil toc:nil todo:nil tasks:nil tags:nil date:nil
#+OPTIONS:     skip:nil author:nil email:nil creator:nil timestamp:nil
#+INFOJS_OPT:  view:nil toc:nil ltoc:t mouse:underline buttons:0 path:http://orgmode.org/org-info.js