StructOpt book

Help messages

In clap, help messages for the whole binary can be specified via App::about and App::long_about while help messages for individual arguments can be specified via Arg::help and Arg::long_help".

long_* variants are used when user calls the program with --help and "short" variants are used with -h flag. In structopt, you can use them via raw methods, for example:

# use structopt::StructOpt;

#[derive(StructOpt)]
#[structopt(about = "I am a program and I work, just pass `-h`")]
struct Foo {
  #[structopt(short, help = "Pass `-h` and you'll see me!")]
  bar: String
}

For convenience, doc comments can be used instead of raw methods (this example works exactly like the one above):

# use structopt::StructOpt;

#[derive(StructOpt)]
/// I am a program and I work, just pass `-h`
struct Foo {
  /// Pass `-h` and you'll see me!
  bar: String
}

Doc comments on top-level will be turned into App::about/long_about call (see below), doc comments on field-level are Arg::help/long_help calls.