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struct Args {
thing: String,
number: u32,
shout: bool,
}
fn parse_args() -> Result<Args, lexopt::Error> {
use lexopt::prelude::*;
let mut thing = None;
let mut number = 1;
let mut shout = false;
let mut parser = lexopt::Parser::from_env();
while let Some(arg) = parser.next()? {
match arg {
Short('n') | Long("number") => {
number = parser.value()?.parse()?;
}
Long("shout") => {
shout = true;
}
Value(val) if thing.is_none() => {
thing = Some(val.string()?);
}
Long("help") => {
println!("Usage: hello [-n|--number=NUM] [--shout] THING");
std::process::exit(0);
}
_ => return Err(arg.unexpected()),
}
}
Ok(Args {
thing: thing.ok_or("missing argument THING")?,
number,
shout,
})
}
fn main() -> Result<(), lexopt::Error> {
let args = parse_args()?;
let mut message = format!("Hello {}", args.thing);
if args.shout {
message = message.to_uppercase();
}
for _ in 0..args.number {
println!("{}", message);
}
Ok(())
}