clap/examples/derive_ref/custom-bool.rs
Ed Page 4b51b8e253 docs(examples): Steer people to know about about vs long_about
`#[clap(about)]` only overrides `about`.  If the doc comment also sets
`long_about`, it won't be overridden.  This change is to help raise
visibility of reseting `long_about` in these cases.
2022-01-10 18:47:24 -06:00

32 lines
857 B
Rust

use clap::Parser;
#[derive(Parser, Debug, PartialEq)]
#[clap(author, version, about, long_about = None)]
struct Opt {
// Default parser for `try_from_str` is FromStr::from_str.
// `impl FromStr for bool` parses `true` or `false` so this
// works as expected.
#[clap(long, parse(try_from_str))]
foo: bool,
// Of course, this could be done with an explicit parser function.
#[clap(long, parse(try_from_str = true_or_false), default_value_t)]
bar: bool,
// `bool` can be positional only with explicit `parse(...)` annotation
#[clap(parse(try_from_str))]
boom: bool,
}
fn true_or_false(s: &str) -> Result<bool, &'static str> {
match s {
"true" => Ok(true),
"false" => Ok(false),
_ => Err("expected `true` or `false`"),
}
}
fn main() {
let opt = Opt::parse();
dbg!(opt);
}