This patch:
* Removes the `ArgSettings::Global` variant, and replaces all
users of it to `Arg::global(...)`. The variant itself is lifted up
into a field on Arg. This was deprecated in clap 2.32.0.
* Removes AppFlags::PropagateGlobalValuesDown. This was deprecated in
clap 2.27.0.
* Removes `Arg::empty_values`. This was deprecated in clap 2.30.0.
* Removes `ArgMatches::usage`. This was deprecated in clap 2.32.0.
subcommands
This commit changes the internal ID to a u64 which will allow for
greater optimizations down the road. In addition, it lays the ground
work for allowing users to use things like enum variants as argument
keys instead of strings.
The only downside is each key needs to be hashed (the implementation
used is an FNV hasher for performance). However, the performance gains
in faster iteration, comparison, etc. should easily outweigh the single
hash of each argument.
Another benefit of if this commit is the removal of several lifetime
parameters, as it stands Arg and App now only have a single lifetime
parameter, and ArgMatches and ArgGroup have no lifetime parameter.
Args can now be added to custom help sections. This breaks up the builder pattern a little by adding help section declarations inline, but it's the most intuitive method and doesn't require strange nesting that feels awkward.
```rust
app::new("foo")
.arg(Arg::with_name("arg1")) // under normal headers
.help_heading("SPECIAL")
.arg(Arg::with_name("arg2")) // under SPECIAL: heading
```
Closes#805
Add logic to filter based on hidden long/short.
There is still an issue with the logic in parser.rs use_long_help. This
causes invalid evaluation of whether to show/hide based on long or short help
Complete check for use_long_help, add tests
For version 3, we want the args section to immediately follow
the usage section in the default help message.
One change that I am unhappy with is needing to make "write_arg"
in app/help.rs accept an extra param that makes it suppress the
extra line. This is to prevent an extra blank line from appearing
between args and options in the default help, and seems necessary,
but there might be a better way.
