Pyenv mode integrates Fabián E. Gallina's python.el with the pyenv tool. This gives packages which already use python.el (like python-django) pyenv virtual environment support out-of-the-box.

• Setup the PYENV_VERSION environment variable and python-shell-virtualenv-path custom variable based on user input

• Override your exec-path
• Run external shell scripts
• Manage your pyenv installation
• Deal with virtualenvwrapper

You can simply install the package from Melpa:

M-x package-install RET pyenv-mode

Add following block to your Emacs configuration:

(pyenv-mode)

Now you can specify the pyenv Python version:

M-x pyenv-mode-set

So now when you run inferior Python with:

M-x run-python

The process will start inside the specified Python installation. You can unset the current version with:

M-x pyenv-mode-unset

When you set the Python version with pyenv-mode, the following changes happen automatically:

• compile commands use proper Python version and environment
• flycheck performs syntax checking according to Python version you use
• anaconda-mode search completions, definitions and references respect the chosen environment

You can switch Python versions together with your current project. Drop the following lines into your Emacs init file. When you use projectile switch project with the C-c p p key binding pyenv-mode will activate the environment matched to the project's name.

(require 'pyenv-mode)

(defun projectile-pyenv-mode-set ()
  "Set pyenv version matching project name."
  (let ((project (projectile-project-name)))
    (if (member project (pyenv-mode-versions))
        (pyenv-mode-set project)
      (pyenv-mode-unset))))

(add-hook 'projectile-after-switch-project-hook 'projectile-pyenv-mode-set)