clap/examples/typed-derive.rs

44 lines
1.2 KiB
Rust

use clap::Parser;
use std::error::Error;
#[derive(Parser, Debug)] // requires `derive` feature
struct Args {
/// Implicitly using `std::str::FromStr`
#[clap(short = 'O')]
optimization: Option<usize>,
/// Allow invalid UTF-8 paths
#[clap(short = 'I', value_name = "DIR", value_hint = clap::ValueHint::DirPath)]
include: Option<std::path::PathBuf>,
/// Handle IP addresses
#[clap(long)]
bind: Option<std::net::IpAddr>,
/// Allow human-readable durations
#[clap(long)]
sleep: Option<humantime::Duration>,
/// Hand-written parser for tuples
#[clap(short = 'D', value_parser = parse_key_val::<String, i32>)]
defines: Vec<(String, i32)>,
}
/// Parse a single key-value pair
fn parse_key_val<T, U>(s: &str) -> Result<(T, U), Box<dyn Error + Send + Sync + 'static>>
where
T: std::str::FromStr,
T::Err: Error + Send + Sync + 'static,
U: std::str::FromStr,
U::Err: Error + Send + Sync + 'static,
{
let pos = s
.find('=')
.ok_or_else(|| format!("invalid KEY=value: no `=` found in `{}`", s))?;
Ok((s[..pos].parse()?, s[pos + 1..].parse()?))
}
fn main() {
let args = Args::parse();
println!("{:?}", args);
}