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https://github.com/clap-rs/clap
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eda0ca54c1
Clap has focused on reporting development errors through assertions rather than mixing user errors with development errors. Sometimes, developers need to handle things more flexibly so included in #3732 was the reporting of value accessor failures as internal errors with a distinct type. I've been going back and forth on whether the extra error pessimises the usability in the common case vs dealing with the proliferation of different function combinations. In working on deprecating the `value_of` functions, I decided that it was going to be worth duplicating so long as we can keep the documentation focused.
32 lines
757 B
Rust
32 lines
757 B
Rust
// Note: this requires the `cargo` feature
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use clap::{arg, command, value_parser, ArgEnum};
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, ArgEnum)]
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enum Mode {
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Fast,
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Slow,
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}
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fn main() {
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let matches = command!()
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.arg(
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arg!(<MODE>)
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.help("What mode to run the program in")
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.value_parser(value_parser!(Mode)),
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)
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.get_matches();
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// Note, it's safe to call unwrap() because the arg is required
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match matches
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.get_one::<Mode>("MODE")
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.expect("'MODE' is required and parsing will fail if its missing")
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{
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Mode::Fast => {
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println!("Hare");
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}
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Mode::Slow => {
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println!("Tortoise");
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}
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}
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}
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