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https://github.com/clap-rs/clap
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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.
36 lines
1.2 KiB
Rust
36 lines
1.2 KiB
Rust
use clap::{App, Arg};
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fn main() {
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// There are two ways in which to get a default value, one is to use clap's Arg::default_value
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// method, and the other is to use Rust's built in Option::unwrap_or method.
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//
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// I'll demo both here.
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//
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// First, we'll use clap's Arg::default_value with an "INPUT" file.
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let matches = App::new("myapp")
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.about("does awesome things")
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.arg(
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Arg::new("INPUT")
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.about("The input file to use")
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.default_value("input.txt")
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.index(1),
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)
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// Next we'll use the Option::unwrap_or method on this "CONFIG" option
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.arg(
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Arg::new("CONFIG")
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.about("The config file to use")
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.short('c')
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.takes_value(true),
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)
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.get_matches();
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let input = matches
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.value_of("INPUT")
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.expect("'INPUT' is default and parsing will ensure there always is a value");
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// Using Option::unwrap_or we get the same effect, but without the added help text injection
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let config_file = matches.value_of("CONFIG").unwrap_or("config.json");
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println!("The input file is: {}", input);
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println!("The config file is: {}", config_file);
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}
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