This is a follow up to #3420. Its easy to overlook this because it is only
useful for the conditionals (we actually prevent applying unconditional
defaults to unconditional requireds). This became apparent with the
increased use of defaults with `SetTrue`.
As always, there is the question of when is a bug fix a breaking change.
I'm going to consider this safe since we prevent some instances of this
from even happening and we already did #3420 and this is in line with
those.
Originally I hid all, assuming the flag-only use case but we had to
prevent that from showing up anyways. For the takes_value case, we
should be showing something since we know what it accepts. I decided to
only show the most basic values and hide the rest so as to not overwhelm
the user with redundant options and hope the user recognizes they are
redundant.
Now that flags can have meaningful defaults and with defaults being
implicitly set for certain actions, they appear in help but don't quite
make sense.
This is mostly about avoiding criterion's build times when just
developing clap itself.
I'm assuming the derive test changed because criterion's clap v2 isn't
in the dependency tree anymore.
Actions were inspired by Python and Python does not implicitly default
any field when an action is given. From a Builder API perspective, this
seemed fine because we tend to focus the Builder API on giving the user
all information so they can make their own decisions. When working on
the Derive API, this became a problem because users were going to have
to migrate from an implied default to an explicit default when a common
default is good enough most of the time. This shouldn't interfere with
Builder users getting more details when needed.
This also highlighted two problems
- We set the index for defaults
- We don't debug_assert when applying conditional requirements with a
default present
This will make it easier to divide off parser logic for adding in
actions.
This does mean we can't provide error reporting on bad values with
`bool` but
- We should have also been doing that for `from_flag`
- We'll be dropping this soon in clap4 anyways
This round out the new style actions and allow us to start deprecating
occurrences.
As part of an effort to unify code paths, this does change flag parsing
to do splits. This will only be a problem if the user enables splits
but we'll at least not crash. Once we also address #3776, we'll be able
to have envs all work the same.
This is the minimum set of actions for the derive to move off of
`parse`. These are inspired by Python's native actions.
These new actions have a "unified" behavior with defaults/envs. This
mostly means that occurrences aren't tracked. Occurrences were used as
a substitute for `ValueSource` or for counting values. Both cases
shouldn't be needed anymore but we can re-evaluate this later if needed.
