//! Consume a named argument with fallback to environment variable use bpaf::*; #[allow(dead_code)] #[derive(Clone, Debug)] struct Opts { pub key: String, } pub fn main() { let key = long("key") .env("ACCESS_KEY") .help("access key to use") .argument::("KEY"); let opts = construct!(Opts { key }).to_options().run(); println!("{:?}", opts); }