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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...
}
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