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//! How to use environment variable fallback an how it
//! interacts with `default_value`.
//!
//! Running this example with --help prints this message:
//! -----------------------------------------------------
//! env 0.3.25
//! Example for allowing to specify options via environment variables
//!
//! USAGE:
//! env [OPTIONS] --api-url <api-url>
//!
//! FLAGS:
//! -h, --help Prints help information
//! -V, --version Prints version information
//!
//! OPTIONS:
//! --api-url <api-url> URL for the API server [env: API_URL=]
//! --retries <retries> Number of retries [env: RETRIES=] [default: 5]
//! -----------------------------------------------------
use structopt::StructOpt;
/// Example for allowing to specify options via environment variables.
#[derive(StructOpt, Debug)]
#[structopt(name = "env")]
struct Opt {
// Use `env` to enable specifying the option with an environment
// variable. Command line arguments take precedence over env.
/// URL for the API server
#[structopt(long, env = "API_URL")]
api_url: String,
// The default value is used if neither argument nor environment
// variable is specified.
/// Number of retries
#[structopt(long, env = "RETRIES", default_value = "5")]
retries: u32,
}
fn main() {
let opt = Opt::from_args();
println!("{:#?}", opt);
}
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