Crate strict_env[][src]

Use this crate to parse environment variables into any type that implements FromStr.

Basic usage

std::env::set_var("PORT", "9001");
let port: u16 = strict_env::parse("PORT")?;
assert_eq!(port, 9001);

Usage with remote types

If you need to parse a type that originates from an external crate and does not implement FromStr, you can wrap the value in a newtype that implements the trait.

// std::time::Duration does not implement FromStr!
struct ConfigDuration(std::time::Duration);

// Custom implementation using the awesome humantime crate
impl std::str::FromStr for ConfigDuration {
    type Err = humantime::DurationError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let inner = humantime::parse_duration(s)?;

// Now we can use strict_env! (But we might have to use the turbofish.)
std::env::set_var("CACHE_DURATION", "2 minutes");
let cache_duration = strict_env::parse::<ConfigDuration>("CACHE_DURATION")?.0;
assert_eq!(cache_duration.as_secs(), 120);



Error type for this library.



Parse an environment variable into a value that implements FromStr.


Like parse, but allows the environment variable to be missing or empty.


Like parse, but falls back to a default value when the environment variable is missing or empty.