Because we gradually build the `ArgGroup` as we parse the YAML, we don't
use `ArgGroup::new`. Clap3 introduced an internal `id` in addition to
the public `name` and it appears that this custom initialization code
was not updated.
This shows the problem with publically exposing `impl Default`.
Choices:
- Remove `impl Default`
- Always valid
- Requires spreading invariants
- Callers can't implement code the same way we do
- Add `ArgGroup::name`
- Can be constructed in an invalid state
- Centralizes invariants
- A caller could implement code like the yaml logic
I decided to go with `ArgGroup::name`.
Fixes#2719
Improved the `impl`s of `From` for `&'help Yaml` to use expects with useful messages instead of unwraps. Also made changes to avoid potentially fetching redundant data from YAML hashes and unwrapping the same data multiple times. Finally, there are tests to ensure the panics are correct.
This commit introduces a new feature called `"regex"`. It adds a new
function `validator_regex` to `Arg` and was inspired by the discussion
in #1968. The name `validator_regex` was chosen instead of
`regex_validator` to make sure that the developer keeps in mind that
there may only be a single `Validator` on an `Arg`.
The feature can be used with YAML files, however there is no proper
pattern in `clap_app!` (yet).
The YAML null value is called `null` in YAML, not `Null`. yaml-rust
handles those values according to spec, so we should use the correct
capitalization.
See https://yaml.org/spec/1.2/spec.html#id2803362 for more
information.
Adds new method/attribute `Arg::value_hint`, taking a `ValueHint` enum
as argument. The hint can denote accepted values, for example: paths,
usernames, hostnames, commands, etc.
This initial implementation supports hints for the zsh and fish
completion generators, support for other shells can be added later.
this implements Arg::short_alias, Arg::short_aliases,
Arg::short_visible_alias, and Arg::short_visible_aliases in addition to
adding their associated tests
