Available on crate feature
unstable-doc
only.Expand description
Example: Custom Types (Derive API)
use clap::Parser;
use std::error::Error;
#[derive(Parser, Debug)] // requires `derive` feature
struct Args {
/// Implicitly using `std::str::FromStr`
#[arg(short = 'O')]
optimization: Option<usize>,
/// Allow invalid UTF-8 paths
#[arg(short = 'I', value_name = "DIR", value_hint = clap::ValueHint::DirPath)]
include: Option<std::path::PathBuf>,
/// Handle IP addresses
#[arg(long)]
bind: Option<std::net::IpAddr>,
/// Allow human-readable durations
#[arg(long)]
sleep: Option<humantime::Duration>,
/// Hand-written parser for tuples
#[arg(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);
}
This requires enabling the derive
feature flag.
Help:
$ typed-derive --help
Usage: typed-derive[EXE] [OPTIONS]
Options:
-O <OPTIMIZATION> Implicitly using `std::str::FromStr`
-I <DIR> Allow invalid UTF-8 paths
--bind <BIND> Handle IP addresses
--sleep <SLEEP> Allow human-readable durations
-D <DEFINES> Hand-written parser for tuples
-h, --help Print help information
Optimization-level (number)
$ typed-derive -O 1
Args { optimization: Some(1), include: None, bind: None, sleep: None, defines: [] }
$ typed-derive -O plaid
? failed
error: Invalid value "plaid" for '-O <OPTIMIZATION>': invalid digit found in string
For more information try '--help'
Include (path)
$ typed-derive -I../hello
Args { optimization: None, include: Some("../hello"), bind: None, sleep: None, defines: [] }
IP Address
$ typed-derive --bind 192.0.0.1
Args { optimization: None, include: None, bind: Some(192.0.0.1), sleep: None, defines: [] }
$ typed-derive --bind localhost
? failed
error: Invalid value "localhost" for '--bind <BIND>': invalid IP address syntax
For more information try '--help'
Time
$ typed-derive --sleep 10s
Args { optimization: None, include: None, bind: None, sleep: Some(Duration(10s)), defines: [] }
$ typed-derive --sleep forever
? failed
error: Invalid value "forever" for '--sleep <SLEEP>': expected number at 0
For more information try '--help'
Defines (key-value pairs)
$ typed-derive -D Foo=10 -D Alice=30
Args { optimization: None, include: None, bind: None, sleep: None, defines: [("Foo", 10), ("Alice", 30)] }
$ typed-derive -D Foo
? failed
error: Invalid value "Foo" for '-D <DEFINES>': invalid KEY=value: no `=` found in `Foo`
For more information try '--help'
$ typed-derive -D Foo=Bar
? failed
error: Invalid value "Foo=Bar" for '-D <DEFINES>': invalid digit found in string
For more information try '--help'