This was ported over from the usage parser which modeled after docopt.
We just never got around to implementing the rest of the syntax.
However, when considering this as a standalone feature, an
`arg!(--flag <value>)`, outside of other context, should be optional.
This is how the help would display it.
Fixes#4206
In looking at other help output, I noticed that they use two spaces, in
place of clap's 4, and it doesn't suffer from legibility. If it
doesn't make the output worse, let's go ahead and make it as dense so we
fit more content on the screen.
This is a part of #4132
I see them fulfilling two roles
- A form of bolding
- As a callback to their placeholder in usage
However, it is a bit of an unpolished look and no other CLI seems to do
it. This looks a bit more proefessional. We have colored help for
formatting and I think the sections relation to usage will be clear
enough.
Documenting the existing behavior is challenging which suggests it can
cause user confusion. So long as its not too hard to explicitly
specify actions, we should just do it.
Fixes#4057
multiple_values is now just book keeping for the builder, instead people
should look to actions and `num_args`.
The meaning for it was a little weird anyways.
This is prep for moving the derive tests. Besides organizing the test
folder for each API, this should reduce link time at the cost of
re-compiling more when a test changes.
This is intended to replace the runtime usage parser and is not meant to
be a complete API in of itself, like `clap_app!`. What is in scope is
everything that visually makes sense as in a usage string (see
[docopt](http://docopt.org/) for inspiration). General setting of
attributes is out of scope.
This deviates from both `clap_app` and the runtime usage parser
- `clap_app` supported multiple values but has a bug because we made
`Arg::value_name` non-appending, so we aren't supporting this yet
- We do not yet support optional flags that take a value
- In both, `...` is multiple occurrences and values while its only
multiple occurrences for us
- We explicitly support optional values for flags
- Unlike `clap_app`, our name is optional
- Unlike runtime usage parser, our name syntax is simpler
- Unlike runtime usage parser, our name syntax does not allow modifiers
Its more limited than I would like. Hopefully some people better with
macros can expand the feature set and turn more runtime errors into
compile-time errors.
This is to prepare for deprecating the runtime usage parser (#8).
For those that want the original behavior, you can usxe
`arg.help_heading(Some("FLAGS"))` on your flags. Limitations:
- This will not give you a special sort order
- This will not get a `[FLAGS]` added to usage
For templates, we removed `{unified}` and `{flags}`. To help people
catch these, a debug_assert was added.
I'm unsure but I think there might be a change in behavior in calcuating
when to show `[OPTION]` in usage. The old code only looked at
`required` while flags looked only at arg groups. We now look at both.
Ideally we'd add these in `_build` and remove special casing for
no-groups except in the sort order of groups. I feel like thats best
left for later.
This also reduced the scope of `App`s public API.
`get_*_with_no_heading` seemed a bit specialized to be in the public
API. #2853 looks at splitting it out into its own PR.
BREAKING CHANGE: Multiple
- `UnifiedHelpMessage` removed
- `{flags}` and `{unified}` are removed and will assert when present.
- `get_*_with_no_heading` removed
Fixes#2807
