mirror of
https://github.com/clap-rs/clap
synced 2024-12-13 22:32:33 +00:00
3be8bcf756
This better models what users should be doing and makes it so all comments are more clear. In a prior commit, when a changed an `exit` to `unwrap`, I disliked the fact that I was mixing an unwrap explanatory comment in with another comment. This makes them stand apart.
37 lines
1.3 KiB
Rust
37 lines
1.3 KiB
Rust
use clap::{App, Arg};
|
|
|
|
fn main() {
|
|
// If you have arguments of specific values you want to test for, you can use the
|
|
// .possible_values() method of Arg
|
|
//
|
|
// This allows you specify the valid values for that argument. If the user does not use one of
|
|
// those specific values, they will receive a graceful exit with error message informing them
|
|
// of the mistake, and what the possible valid values are
|
|
//
|
|
// For this example, assume you want one positional argument of either "fast" or "slow"
|
|
// i.e. the only possible ways to run the program are "myprog fast" or "myprog slow"
|
|
let matches = App::new("myapp")
|
|
.about("does awesome things")
|
|
.arg(
|
|
Arg::new("MODE")
|
|
.about("What mode to run the program in")
|
|
.index(1)
|
|
.possible_values(["fast", "slow"])
|
|
.required(true),
|
|
)
|
|
.get_matches();
|
|
|
|
// Note, it's safe to call unwrap() because the arg is required
|
|
match matches
|
|
.value_of("MODE")
|
|
.expect("'MODE' is required and parsing will fail if its missing")
|
|
{
|
|
"fast" => {
|
|
println!("Hare");
|
|
}
|
|
"slow" => {
|
|
println!("Tortoise");
|
|
}
|
|
_ => unreachable!(),
|
|
}
|
|
}
|