Module clap::_cookbook::typed_derive
source · Available on crate feature
unstable-doc only.Expand description
§Example: Custom Types (Derive API)
use clap::builder::TypedValueParser as _;
use clap::Parser;
use std::error::Error;
#[derive(Parser, Debug)] // requires `derive` feature
#[command(term_width = 0)] // Just to make testing across clap features easier
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)>,
/// Support for discrete numbers
#[arg(
long,
default_value_t = 22,
value_parser = clap::builder::PossibleValuesParser::new(["22", "80"])
.map(|s| s.parse::<usize>().unwrap()),
)]
port: usize,
/// Support enums from a foreign crate that don't implement `ValueEnum`
#[arg(
long,
default_value_t = foreign_crate::LogLevel::Info,
value_parser = clap::builder::PossibleValuesParser::new(["trace", "debug", "info", "warn", "error"])
.map(|s| s.parse::<foreign_crate::LogLevel>().unwrap()),
)]
log_level: foreign_crate::LogLevel,
}
/// 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()?))
}
mod foreign_crate {
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub enum LogLevel {
Trace,
Debug,
Info,
Warn,
Error,
}
impl std::fmt::Display for LogLevel {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let s = match self {
Self::Trace => "trace",
Self::Debug => "debug",
Self::Info => "info",
Self::Warn => "warn",
Self::Error => "error",
};
s.fmt(f)
}
}
impl std::str::FromStr for LogLevel {
type Err = String;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s {
"trace" => Ok(Self::Trace),
"debug" => Ok(Self::Debug),
"info" => Ok(Self::Info),
"warn" => Ok(Self::Warn),
"error" => Ok(Self::Error),
_ => Err(format!("Unknown log level: {s}")),
}
}
}
}
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
--port <PORT> Support for discrete numbers [default: 22] [possible values: 22, 80]
--log-level <LOG_LEVEL> Support enums from a foreign crate that don't implement `ValueEnum` [default: info] [possible values: trace, debug, info, warn, error]
-h, --help Print help
Optimization-level (number)
$ typed-derive -O 1
Args { optimization: Some(1), include: None, bind: None, sleep: None, defines: [], port: 22, log_level: Info }
$ 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: [], port: 22, log_level: Info }
IP Address
$ typed-derive --bind 192.0.0.1
Args { optimization: None, include: None, bind: Some(192.0.0.1), sleep: None, defines: [], port: 22, log_level: Info }
$ 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: [], port: 22, log_level: Info }
$ 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)], port: 22, log_level: Info }
$ 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'.
Discrete numbers
$ typed-derive --port 22
Args { optimization: None, include: None, bind: None, sleep: None, defines: [], port: 22, log_level: Info }
$ typed-derive --port 80
Args { optimization: None, include: None, bind: None, sleep: None, defines: [], port: 80, log_level: Info }
$ typed-derive --port
? failed
error: a value is required for '--port <PORT>' but none was supplied
[possible values: 22, 80]
For more information, try '--help'.
$ typed-derive --port 3000
? failed
error: invalid value '3000' for '--port <PORT>'
[possible values: 22, 80]
For more information, try '--help'.
Enums from crates that can’t implement ValueEnum
$ typed-derive --log-level debug
Args { optimization: None, include: None, bind: None, sleep: None, defines: [], port: 22, log_level: Debug }
$ typed-derive --log-level error
Args { optimization: None, include: None, bind: None, sleep: None, defines: [], port: 22, log_level: Error }
$ typed-derive --log-level
? failed
error: a value is required for '--log-level <LOG_LEVEL>' but none was supplied
[possible values: trace, debug, info, warn, error]
For more information, try '--help'.
$ typed-derive --log-level critical
? failed
error: invalid value 'critical' for '--log-level <LOG_LEVEL>'
[possible values: trace, debug, info, warn, error]
For more information, try '--help'.