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