pip-sync --keep-existing

[graingert]

#1166
pypa/pip#53

What's the problem this feature will solve?

I've enabled #1166 which works great to remind people to upgrade their packages - but some people add additional local packages but don't add them to the requirements.txt

Describe the solution you'd like

a pip-sync --keep-existing flag that worked with pip-sync --keep-existing --dry-run to behave in the same way as the proposed pypa/pip#53

Alternative Solutions

• a requirements-dev-specific.txt in .gitignore for additional deps?
• I could just wait for them to do it in pip directly

Additional context

pip-sync --keep-existing is kind-of odd without --dry-run as it's exactly the same as pip install -r requirements.txt

[AndydeCleyre]

Can you please state more specifically what pip-sync --keep-existing and pip-sync --keep-existing --dry-run are expected to do, and what the initial problem is?

Is the behavior you're after the same as currently achieved with pip-sync --dry-run <shared.txt> <personal.txt>?

[graingert]

Is the behavior you're after the same as currently achieved with pip-sync --dry-run <shared.txt> <personal.txt>?

Ooh I think so - is there a way to ignore the <personal.txt> file if it's missing?

[AndydeCleyre]

That's probably easiest (best?) handled by shell globbing/scripting, and a file naming convention. What do you think?

[graingert]

Yeah that's probably better