Clap has focused on reporting development errors through assertions
rather than mixing user errors with development errors. Sometimes,
developers need to handle things more flexibly so included in #3732 was
the reporting of value accessor failures as internal errors with a
distinct type. I've been going back and forth on whether the extra
error pessimises the usability in the common case vs dealing with the
proliferation of different function combinations. In working on
deprecating the `value_of` functions, I decided that it was going to be
worth duplicating so long as we can keep the documentation focused.
Like was said in #2435, this is what people would expect.
While we should note this in a compatibility section in the changelog, I
do not consider this a breaking change since we should be free to adjust
the help output as needed. We are cautious when people might build up
their own content around it (like #3312) but apps should already handle
this with `--help` so this shouldn't be a major change.
We aren't offering a way for people to disable this, assuming people
won't need to. Longer term, we are looking at support "Actions" (#3405)
and expect those to help customize the flags. We'll need something
similar for the `help` subcommand.
Fixes#3440
This is a part of #2717
Some settings didn't get getters because
- They are transient parse settings (e.g. ignore errors)
- They get propagated to args and should be checked there
`is_allow_hyphen_values_set` is a curious case. In some cases, we only
check the app and not an arg. This seems suspicious.
This creates distinct tutorial examples from complex feature examples
(more how-tos). Both sets are getting builder / derive versions (at
least the critical ones).
