Add a single character shortcut for --no-reuse-existing-virtualenvs

[johnthagen]

How would this feature be useful?

A common way to use Nox that saves a lot of time when re-running sessions over and over by avoiding recreating venvs is to set:

nox.options.reuse_existing_virtualenvs = True

You can see the pip developers use this:

• https://github.com/pypa/pip/blob/main/noxfile.py#L19

When dependencies do change, the developer can then run:

nox --no-reuse-existing-virtualenvs -s test

Given this can be a very common work flow, avoiding having to type out --no-reuse-existing-virtualenvs on the command line would be a great improvement to UX.

A note on tox

What I'm describing above is also the default workflow for tox users. Many people moving from tox will be familiar with this workflow. (e.g. tox re-uses venvs by default, and tox -r is an opt-in recreation).

Describe the solution you'd like

Add a new alias for --no-reuse-existing-virtualenvs, for example -C for "Create"

nox -C -s test

[johnthagen]

Related to #488

[ktbarrett]

The CLI supports multicharacter short options and does not currently use -n (which would cause ambiguity), so it may be possible to use the more intuitive -nr short option.

[johnthagen]

-nr would also be a suitable fix for this if the team agrees.

[DiddiLeija]

I don't see any blockers to do this. Any thoughts @wntrblm/nox?

[crwilcox]

By default environments are destroyed and recreated, so wouldn't this be a noop?

[johnthagen]

By default environments are destroyed and recreated, so wouldn't this be a noop?

@crwilcox Not if the user has set in their noxfile.py:

nox.options.reuse_existing_virtualenvs = True

[crwilcox]

Alright. So, to me this sort of feels like an antipattern, but since we already have the long flag, I'd be okay with adding -nr.

Basically, I don't know how prevalent setting args in noxfile.py really is, but as it is allowed, that might not be that relevant ;)

[johnthagen]

I don't know how prevalent setting args in noxfile.py really is, but as it is allowed, that might not be that relevant

The pip developers seem to like them 😄

• https://github.com/pypa/pip/blob/main/noxfile.py#L19