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Diffstat (limited to 'clap/examples/07_option_args.rs')
-rw-r--r-- | clap/examples/07_option_args.rs | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/clap/examples/07_option_args.rs b/clap/examples/07_option_args.rs new file mode 100644 index 0000000..85ff0e5 --- /dev/null +++ b/clap/examples/07_option_args.rs @@ -0,0 +1,71 @@ +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... +} |