use clap::{App, Arg}; fn main() { // Option arguments are those that take an additional value, such as "-c value". In clap they // support three types of specification, those with short() as "-o some", or those with long() // as "--option value" or "--option=value" // // Options also support a multiple setting, which is discussed in the example below. let matches = App::new("MyApp") // Regular App configuration goes here... // Assume we have an application that accepts an input file via the "-i file" // or the "--input file" (as well as "--input=file"). // Below every setting supported by option arguments is discussed. // NOTE: You DO NOT need to specify each setting, only those which apply // to your particular case. .arg( Arg::new("input") .about("the input file to use") // Displayed when showing help info .takes_value(true) // MUST be set to true in order to be an "option" argument .short('i') // This argument is triggered with "-i" .long("input") // This argument is triggered with "--input" .multiple(true) // Set to true if you wish to allow multiple occurrences // such as "-i file -i other_file -i third_file" .required(true) // By default this argument MUST be present // NOTE: mutual exclusions take precedence over // required arguments .requires("config") // Says, "If the user uses "input", they MUST // also use this other 'config' arg too" // Can also specify a list using // requires_all(Vec<&str>) .conflicts_with("output"), // Opposite of requires(), says "if the // user uses -a, they CANNOT use 'output'" // also has a conflicts_with_all(Vec<&str>) // and an exclusive(true) ) .arg("-c, --config=[FILE] 'the config file to use'") .arg(" 'the output file to use'") .get_matches(); // We can find out whether or not "input" was used if matches.is_present("input") { println!("An input file was specified"); } // We can also get the value for "input" // // NOTE: If we specified multiple(), this will only return the _FIRST_ // occurrence if let Some(ref in_file) = matches.value_of("input") { println!("An input file: {}", in_file); } // If we specified the multiple() setting we can get all the values if let Some(in_v) = matches.values_of("input") { for in_file in in_v { println!("An input file: {}", in_file); } } // We can see how many times the option was used with the occurrences_of() method // // NOTE: Just like with flags, if we did not specify the multiple() setting this will only // return 1 no matter how many times the argument was used (unless it wasn't used at all, in // in which case 0 is returned) println!( "The \"input\" argument was used {} times", matches.occurrences_of("input") ); // Continued program logic goes here... }