I like to be able to test things interactively in a Python shell when exploring a new package. I also don’t like to exit Emacs when I don’t have to. So I’d like to be able to run C-c C-p (or run-python) directly from Emacs.

I use the pyvenv package to manage virtual environments within Emacs. It works well, but it doesn’t automaticlly set the correct Python interpreter that I expect when I change virtual environments.

So I added this to my init.el:

(use-package pyvenv
  :ensure t
  (pyvenv-mode t)

  ;; Set correct Python interpreter
  (setq pyvenv-post-activate-hooks
        (list (lambda ()
                (setq python-shell-interpreter (concat pyvenv-virtual-env "bin/python3")))))
  (setq pyvenv-post-deactivate-hooks
        (list (lambda ()
                (setq python-shell-interpreter "python3")))))

Now, when I press C-c C-p, the Python shell interpreter that starts is the one in the virtual environment.

So my workflow is this: activate the virtual environment with M-x pyvenv-activate, experiment in a Python shell (started with C-c C-p), profit.

(I use lsp-mode and Python Language Server for IDE-like features, but that is another post…)