parenv

Environment variable parser with a clap style derive macro and elm style error reporting.

Installation

cargo add parenv

Usage

Here are some important features you should know about.

• parenv relies on the FromStr trait to parse environment variables into the specified type.
• The documentation comment on each field is used as the description for the corresponding environment variable.
• To make a field optional, wrap the type with an Option.
• To set a default value for a field, use #[parenv(default = "value")] on the field.
• To set a prefix value, set the attribute #[parenv(prefix = "ENV_")] on your struct.
• To set a suffix value, set the attribute #[parenv(suffix = "_ARG")] on your struct.

use std::{net::SocketAddr, path::PathBuf};

use parenv::Environment;

#[derive(Debug, Environment)]
#[parenv(prefix = "ENV_", suffix = "_ARG")]
struct Env {
    /// The cat
    cat: Option<u8>,
    /// The dog
    dog: SocketAddr,
    /// The file
    file: PathBuf,
    /// The bird (with default)
    #[parenv(default = "10")]
    bird: u8,
}

fn main() {
    let env = Env::parse();
    dbg!(env.cat, env.dog, env.file, env.bird);
}

Demo