Clearer name for --only-keep?

[pgarrison]

The issue

Today I tried to teach three of my coworkers how to use the --only-keep option, and they found the name pretty confusing.

The effect of --only-keep is to remove packages from the working set. On the face of it, "keep" and "remove" are opposites: this is the source of the confusion. "Only keep" suggests that the command only keeps dependencies, and does not add/remove any.

Usage examples:

• pdm sync --only-keep --prod: This was the example from the original PR for --only-keep. This can be read naturally as "only keep production dependencies."
• pdm sync --prod --only-keep: With --only-keep after --prod, the interpretation is unclear.
• pdm sync --only-keep -d: By analogy with the first example, a user could read this as "only keep dev dependencies", but that is not what the command does, since prod dependencies are also included.
• pdm sync -G test --only-keep -d: For a user who understands sync, -G, and -d, but is unfamiliar with --only-keep, this command is totally confusing.

Behavior of --only-keep

As far as I understand, --only-keep does both of the following:

1. Remove from the working set any packages that are not in the lockfile (what --clean does)
2. Remove from the working set any packages that are in an optional or dev dependency group that is unselected (with the caveat that a plain pdm sync --only-keep selects all optional and dev dependencies).

Is this correct?

Alternative names

Since --only-keep is similar to --clean but does strictly more, I think a related name like --clean-unselected would be great. (I think --clean is well-named: I asked one of my co-workers who has never used --clean before what he expected it to do and he was mostly correct.)

Some other ideas:

• --deep-clean
• --clean-extra
• --remove-unselected
• --drop-optional

Perhaps we can discuss here and come up with a clearer name?

[frostming]

--clean-unselected looks better to me, maybe we can add it as an alias first