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