vendor/structopt/examples/example.rs

   1 //! Somewhat complex example of usage of structopt.
   2
   3 use structopt::StructOpt;
   4
   5 #[derive(StructOpt, Debug)]
   6 #[structopt(name = "example")]
   7 /// An example of StructOpt usage.
   8 struct Opt {
   9     // A flag, true if used in the command line.
  10     #[structopt(short, long)]
  11     /// Activate debug mode
  12     debug: bool,
  13
  14     // An argument of type float, with a default value.
  15     #[structopt(short, long, default_value = "42")]
  16     /// Set speed
  17     speed: f64,
  18
  19     // Needed parameter, the first on the command line.
  20     /// Input file
  21     input: String,
  22
  23     // An optional parameter, will be `None` if not present on the
  24     // command line.
  25     /// Output file, stdout if not present
  26     output: Option<String>,
  27
  28     // An optional parameter with optional value, will be `None` if
  29     // not present on the command line, will be `Some(None)` if no
  30     // argument is provided (i.e. `--log`) and will be
  31     // `Some(Some(String))` if argument is provided (e.g. `--log
  32     // log.txt`).
  33     #[structopt(long)]
  34     #[allow(clippy::option_option)]
  35     /// Log file, stdout if no file, no logging if not present
  36     log: Option<Option<String>>,
  37
  38     // An optional list of values, will be `None` if not present on
  39     // the command line, will be `Some(vec![])` if no argument is
  40     // provided (i.e. `--optv`) and will be `Some(Vec<String>)` if
  41     // argument list is provided (e.g. `--optv a b c`).
  42     #[structopt(long)]
  43     optv: Option<Vec<String>>,
  44
  45     // Skipped option: it won't be parsed and will be filled with the
  46     // default value for its type (in this case it'll be an empty string).
  47     #[structopt(skip)]
  48     skipped: String,
  49 }
  50
  51 fn main() {
  52     let opt = Opt::from_args();
  53     println!("{:?}", opt);
  54 }