Module version 

Version Flag

#[command(version)] enables a version flag, as in Clap. The version is the package version (CARGO_PKG_VERSION) of the crate deriving GetArgs, and #[command(version = "1.2.3")] sets it explicitly. Two constants are then generated: VERSION, the version itself, and VERSION_TEXT, the line Clap prints for --version (the command name, a space and the version). The help gains a -V, --version Print version line.

Handling -V and --version

-V and --version make parse and from_args return Err(Error::Version(text)), where text is the struct’s VERSION_TEXT. Like help, this takes priority over missing required arguments, is checked with Error::is_version(), and never prints anything or exits the process:

use getargs_derive::{Error, GetArgs};

#[derive(Debug, GetArgs)]
#[command(name = "copy", version = "1.2.3")]
struct Cli<'a> {
    /// Input file.
    input: &'a str,
}

assert_eq!(Cli::VERSION, "1.2.3");
let error = Cli::from_args(["--version"].into_iter()).unwrap_err();
assert!(error.is_version());
assert_eq!(error, Error::Version("copy 1.2.3"));
assert_eq!(
    Cli::HELP,
    "\
Usage: copy [OPTIONS] <INPUT>

Arguments:
  <INPUT>  Input file

Options:
  -h, --help     Print help
  -V, --version  Print version"
);

With std, print it to standard output and exit successfully, as for help (see Generated Help). -V and --version are only reserved when version is set: a field declaring short name V or long name version is then a compile error. Without version, no version flag is generated and fields may use those names.

Compile-Time Diagnostics

The macro reports a compile error, pointing at the offending attribute or field, for:

• a field using -V or --version while #[command(version)] is set;
• an empty or non-string #[command(version = ...)].