clap/examples/derive_ref/augment_args.rs
Ed Page 647896d929 feat(derive): Expose control over Actions
This is the derive support for #3774 (see also #3775, #3777)

This combined with `value_parser` replaces `parser`.  The main
frustration with this is that `ArgAction::Count` (the replacement for
`parse(from_occurrences)` must be a `u64`.  We could come up with a
magic attribute that is meant to be the value parser's parsed type.  We
could then use `TryFrom` to convert the parsed type to the user's type
to allow more.  That is an exercise for the future.  Alternatively, we
have #3792.

Prep for this included
- #3782
- #3783
- #3786
- #3789
- #3793
2022-06-06 11:35:07 -05:00

30 lines
971 B
Rust

use clap::{arg, Args as _, Command, FromArgMatches as _, Parser};
#[derive(Parser, Debug)]
struct DerivedArgs {
#[clap(short, long, action)]
derived: bool,
}
fn main() {
let cli = Command::new("CLI").arg(arg!(-b - -built).action(clap::ArgAction::SetTrue));
// Augment built args with derived args
let cli = DerivedArgs::augment_args(cli);
let matches = cli.get_matches();
println!(
"Value of built: {:?}",
*matches.get_one::<bool>("built").unwrap()
);
println!(
"Value of derived via ArgMatches: {:?}",
*matches.get_one::<bool>("derived").unwrap()
);
// Since DerivedArgs implements FromArgMatches, we can extract it from the unstructured ArgMatches.
// This is the main benefit of using derived arguments.
let derived_matches = DerivedArgs::from_arg_matches(&matches)
.map_err(|err| err.exit())
.unwrap();
println!("Value of derived: {:#?}", derived_matches);
}