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use gumdrop::Options;
// Defines options that can be parsed from the command line.
//
// `derive(Options)` will generate an implementation of the trait `Options`.
// Each field must either have a `Default` implementation or an inline
// default value provided.
//
// (`Debug` is only derived here for demonstration purposes.)
#[derive(Debug, Options)]
struct MyOptions {
// Contains "free" arguments -- those that are not options.
// If no `free` field is declared, free arguments will result in an error.
#[options(free)]
free: Vec<String>,
// Boolean options are treated as flags, taking no additional values.
// The optional `help` attribute is displayed in `usage` text.
#[options(help = "print help message")]
help: bool,
// Non-boolean fields will take a value from the command line.
// Wrapping the type in an `Option` is not necessary, but provides clarity.
#[options(help = "give a string argument")]
string: Option<String>,
// A field can be any type that implements `FromStr`.
// The optional `meta` attribute is displayed in `usage` text.
#[options(help = "give a number as an argument", meta = "N")]
number: Option<i32>,
// A `Vec` field will accumulate all values received from the command line.
#[options(help = "give a list of string items")]
item: Vec<String>,
// The `count` flag will treat the option as a counter.
// Each time the option is encountered, the field is incremented.
#[options(count, help = "increase a counting value")]
count: u32,
// Option names are automatically generated from field names, but these
// can be overriden. The attributes `short = "?"`, `long = "..."`,
// `no_short`, and `no_long` are used to control option names.
#[options(no_short, help = "this option has no short form")]
long_option_only: bool,
}
fn main() {
// Parse options from the environment.
// If there's an error or the user requests help,
// the process will exit after giving the appropriate response.
let opts = MyOptions::parse_args_default_or_exit();
println!("{:#?}", opts);
}
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