benefit of passing env var as Extension

[mrl5]

Is there any benefit of passing a value taken from environment variable via .layer(Extension(env_var)) rather than reading it directly in handler where it's needed?

use axum::{Extension, Router};
use axum::routing::get;

fn get_router() -> Router {
    Router::new()
        .route("/foo", get(get_foo_ext))
        .layer(Extension(std::env::var("FOO").unwrap_or_else(|_| "bar".to_owned())))
}

async fn get_foo_ext(Extension(foo): Extension<String>) -> String {
    foo
}

vs

use axum::Router;
use axum::routing::get;

fn get_router() -> Router {
    Router::new()
        .route("/foo", get(get_foo_env))
}

async fn get_foo_env() -> String {
    std::env::var("FOO").unwrap_or_else(|_| "bar".to_owned())
}

[davidpdrsn]

Not unless you wanna easily overwrite the value in a test or something.