#env #env-var #var #struct #string #debugging #derive #env-init #env-once

env_init

Small crate to help initializing environment structs

3 releases

Uses new Rust 2024

new 0.1.2 Apr 17, 2025
0.1.1 Apr 17, 2025
0.1.0 Apr 16, 2025

#1394 in Rust patterns

Download history 200/week @ 2025-04-12

200 downloads per month

MIT license

13KB
233 lines

EnvInit

This is a small crate to help initializing environment variable structs, accepting any environment provider and by default automatically parsing the strings into their corresponding types in the struct.

Example Usage with dotenvy

.env

SOME_INT=42
SOME_STR=Hello
SOME_OTHER_STR=World

main.rs

use env_init::{Env, EnvGetter, EnvOnce};

#[derive(Debug)]
pub struct MyEnv {
    some_int: i32,
    some_other_int: i32,
    opt_int: Option<i32>,
    some_str: &'static str,
    owned_str: String
}

impl Env for MyEnv {
    fn new() -> Self {
        // Defining a getter that calls dotenvy::var
        let g = EnvGetter::new(|x| dotenvy::var(x));

        Self {
            some_int: g.owned_var("SOME_INT"),
            some_other_int: g.owned_var_or("SOME_OTHER_INT", 100),
            opt_int: g.owned_var_try("SOME_OPTIONAL_INT").ok(),
            some_str: g.var::<String>("SOME_STR").as_str(),
            owned_str: g.owned_var("SOME_OTHER_STR"),
        }
    }
}

// Our global environment object
pub static ENV: EnvOnce<MyEnv> = EnvOnce::new();

fn main() {
    dotenvy::dotenv().unwrap();
    ENV.init();

    assert_eq!(ENV.some_int, 42);
    assert_eq!(ENV.some_other_int, 100);
    assert_eq!(ENV.opt_int, None);
    assert_eq!(ENV.some_str, "Hello");
    assert_eq!(ENV.owned_str, "World");
}

Dependencies

~225–670KB
~15K SLoC