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.
The macro `yaml_opt_str` is only used in `yaml_tuple3`, which again is
only used for `default_value_if`. Unfortunately, the current test
doesn't make sense, as a v.is_null() indicates a Yaml::Null, on wich
`as_str()` always returns `None`. Instead, the condition should be
negated, as the documentation of `default_value_if` hints:
> **NOTE:** If using YAML the values should be laid out as
> follows (`None` can be represented as `null` in YAML)
The case `$v.is_null()` should therefore lead to `None`, whereas all
other cases should be interpreted `as_str()`.
While reading the code for the yaml translation, I've noticed that
there is a bug in the macro `yaml_opt_str` as well as a wrong `null`
value in the test fixture.
These tests add the expected behaviour on the given fixture, e.g.
prog
and
prog <WRONG>
where `<WRONG>` is **not** `other` should yield `None` for
`"positional2"`, whereas
prog other
should yield "something" and
prog --flag ARBITRARY_VALUE
should yield "some". The first two tests
- default_value_if_not_triggered
- default_value_if_not_triggered_by_argument
fail, as the second positional arguments *gets set*, although its
conditions aren't fulfilled.
Previously there were separate tags for this, {before-help-padded} and
{after-help-padded}. Those have been removed and the default ones
given their behavior.
This makes some changes to the template system:
- Template tags for optional items (like {author}) now expand to
nothing when the value is unset instead of a default string (like
"unknown author").
- Many template tags now emit line-wrapped output to match
write_default_help.
- Items with long variants now expand to the appropriate thing for -h
vs --help.
- The now-obsolete {long-about} tag has been removed.
- A few new tags have been added.
These are externally-visible changes, but if this makes it into 3.0
that's probably reasonable?
Note that line-wrapping can have some odd edge cases since it does not
account for preceding/trailing characters on the same line as the tag.
This is already the case in master, but will affect some additional
tags with this changeset. See #2065 for details.
Closes#2002.
