Python setup for Emacs

python-setup.el

;;;========================================
;;; Disclaimer
;;;========================================

;; This configuration relies on use-package: https://github.com/jwiegley/use-package

;;;========================================

;;;========================================
;;; Python
;;;========================================
(use-package python
  :ensure t
  :defer t
  :delight "Py"
  :config
  ;; Remove guess indent python message
  (setq python-indent-guess-indent-offset-verbose nil))

;; Hide the modeline for inferior python processes (as well as R)
(use-package inferior-python-mode
  :ensure nil
  :hook (inferior-python-mode . hide-mode-line-mode))

(use-package hide-mode-line
  :ensure t
  :defer t)

;;; Use poetry to manage packages and when to switch to virtualenvs
;;; See https://python-poetry.org/ for more info
;;; See https://python-poetry.org/docs/managing-environments/ for virtual envs management
(use-package poetry
  :ensure t
  :defer t
  :config
  (setq poetry-tracking-strategy 'switch-buffer)
  (setenv "WORKON_HOME" "~/.cache/pypoetry/virtualenvs")) ;; keeping track of virtualenvs available

;; Buffer formatting on save
(use-package blacken
  :ensure t
  :defer t
  :custom
  (blacken-allow-py36 t)
  (blacken-skip-string-normalization t)
  :hook (python-mode . blacken-mode))

;; numpy docstring for python
(use-package numpydoc
  :ensure t
  :defer t
  :custom
  (numpydoc-insert-examples-block nil)
  (numpydoc-template-long nil)
  :bind (:map python-mode-map
              ("C-c C-n" . numpydoc-generate)))

;;; Next up are packages which are not strictly Python related
;;; and apply for lots of languages, YMMV but it's a good idea to use company for completion
;;; and some form of language server interface (lsp-mode or eglot), this file uses lsp-mode. 

(use-package company
  :ensure t
  :defer t
  :diminish ""
  :custom
  (company-dabbrev-other-buffers t)
  (company-dabbrev-code-other-buffers t)
  ;; M-<num> to select an option according to its number.
  (company-show-numbers t)
  ;; Only 2 letters required for completion to activate.
  (company-minimum-prefix-length 3)
  ;; Do not downcase completions by default.
  (company-dabbrev-downcase nil)
  ;; Even if I write something with the wrong case,
  ;; provide the correct casing.
  (company-dabbrev-ignore-case t)
  ;; Don't wait before completion.
  (company-idle-delay 0)
  ;; No company-mode in shell & eshell
  (company-global-modes '(not eshell-mode shell-mode))
    :hook ((text-mode . company-mode)
           (prog-mode . company-mode)))

;;; `lsp-mode` proper
;;; The config should be relatively agnostic up to here

(use-package lsp-mode
  :ensure t
  :defer t
  :delight " LSP"
  :defines (lsp-keymap-prefix lsp-mode-map)
  :init
  (setq lsp-keymap-prefix "C-c l")
  :custom
  (lsp-keep-workspace-alive nil)
  (lsp-auto-guess-root nil)
  (lsp-eldoc-enable-hover nil)
  (lsp-signature-auto-activate nil)
  (lsp-completion-enable t)
  :hook (lsp-mode-hook . lsp-enable-which-key-integration)
  :commands (lsp lsp-deferred)
  :bind (:map lsp-mode-map
	      ("M-<RET>" . lsp-execute-code-action)))

;; Debugger
(use-package dap-mode
  :ensure t
  :defer t
  :after lsp-mode
  :config
  (dap-auto-configure-mode))

;;; See https://emacs-lsp.github.io/lsp-mode/ for more info
(use-package lsp-pyright
  :ensure t
  :defer t
  :custom
  (lsp-pyright-disable-language-service nil)
  (lsp-pyright-disable-organize-imports nil)
  (lsp-pyright-auto-import-completions t)
  (lsp-pyright-use-library-code-for-types t)
  (lsp-completion-enable t)
  :hook ((python-mode . (lambda ()
			       (poetry-tracking-mode)
			       (require 'lsp-pyright)
			       (lsp-deferred)))))

This gist relies on a couple packages some are Emacs related, some are external tools for which there are Emacs packages:

• LSP-mode: https://emacs-lsp.github.io/lsp-mode/
• poetry : https://python-poetry.org/
• pyenv : https://github.com/pyenv/pyenv (have multiple python versions alongside each other)
• YAPF : https://github.com/google/yapf (which you should install as a dev dependency in your virtual env)

It's a lot so you should probably work your way through each package before just copy/pasting this.
Note that if you use something like anaconda, there are packages like https://github.com/necaris/conda.el and https://github.com/jorgenschaefer/pyvenv, the latter being more agnostic to how virtual envs are managed.