Default root to default-directory if not in a project

[akreisher]

Thanks for this package, I am using it in eshell to automatically "activate" venvs for the current eshell dir with the following snippet:

  (defun my:eshell-insert-pet-venv (path)
    "Advice for adding python venv to eshell PATH."
    (if-let ((venv (pet-virtualenv-root)))
        (cons (expand-file-name "bin/" venv) path)
      path))

  (defun my:enable-eshell-pet ()
    "Automatically activate python env in eshell."
    (interactive)
    (advice-add #'eshell-get-path :filter-return #'my:eshell-insert-pet-venv))

  (defun my:disable-eshell-pet ()
    (advice-remove #'eshell-get-path #'my:eshell-insert-pet-venv))

This works well for directories in recognized projects. When visiting a non-project directory with a venv, however, I run into a problem with pet-virtualenv-root returning the cached venv value even when leaving to another directory with no venv. I traced this to pet-virtualenv-root caching the venv location with a root key of nil (since pet-project-root returns nil). Since this root is used for all non-project dirs, pet-virtualenv-root returns an incorrect value for all the non-project dirs visited after the first one with a recognized venv.

For example, to reproduce with the above code, I can run:

cd /tmp
python -m venv venv
which python3  # /tmp/venv/bin/python3, as expected
cd / 
which python3  # still /tmp/venv/bin/python3,  expected system python

To fix, I just added a default of the current default-directory to the value of root used in pet-virtualenv-root, which causes it to correctly associate the found venv with the searched directory, regardless of whether it is in a project or not. Alternatively, we could not cache venvs with a root of nil, but I figured it would be better like this since root is only used by the caching mechanism here anyways.

[wyuenho]

In this case, shouldn't the solution be to make sure no (root . nil) entry is written into the cache in the first place?

[wyuenho]

See if f615a2fd3557a94642d0f95e52cf1f40decc99f5 works for you