1 | use clap::{arg, command}; |
2 | |
3 | fn main() { |
4 | let matches = command!() // requires `cargo` feature |
5 | .arg( |
6 | arg!(<MODE>) |
7 | .help("What mode to run the program in" ) |
8 | .value_parser(["fast" , "slow" ]), |
9 | ) |
10 | .get_matches(); |
11 | |
12 | // Note, it's safe to call unwrap() because the arg is required |
13 | match matches |
14 | .get_one::<String>("MODE" ) |
15 | .expect("'MODE' is required and parsing will fail if its missing" ) |
16 | .as_str() |
17 | { |
18 | "fast" => { |
19 | println!("Hare" ); |
20 | } |
21 | "slow" => { |
22 | println!("Tortoise" ); |
23 | } |
24 | _ => unreachable!(), |
25 | } |
26 | } |
27 | |