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+extern crate clap;
+
+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::with_name("input")
+ .help("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>)
+ )
+ // NOTE: In order to compile this example, comment out conflicts_with()
+ // and requires() because we have not defined an "output" or "config"
+ // argument.
+ .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(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...
+}