Macro register 

macro_rules! register {
    ($var:ident) => { ... };
    ($var:ident | $err:expr ) => { ... };
    ($($var:ident),* $(,)?) => { ... };
    ($($var:ident | $err:expr),* $(,)?) => { ... };
    ($var:ident = $default:expr) => { ... };
    ($($var:ident = $default:expr),* $(,)?) => { ... };
    ($var:ident = $default:expr; $priority:ident) => { ... };
    ($($var:ident = $default:expr),* $(,)?; $priority:ident) => { ... };
}

Registers one or more environment variables for tracking and validation.

This macro simplifies the process of registering environment variables that your application depends on. Once registered, you can utilize env-inventory’s utilities to load, validate, and manage these environment variables.

Examples

register!("DATABASE_URL", "REDIS_URL", "API_KEY");
register!("LOG_LEVEL" => "debug", "CACHE_SIZE" => 1024);

The first call registers three environment variables: DATABASE_URL, REDIS_URL, and API_KEY. The second call registers two environment variables with default values: LOG_LEVEL with a default of "debug", and CACHE_SIZE with a default of 1024.

Parameters

• $($var:expr),*: A comma-separated list of string literals, each representing an environment variable to register.
• $($var:expr => $default:expr),*: A comma-separated list of pairs, where each pair consists of a string literal representing an environment variable and its default value.

Panics

This macro will panic at compile-time if any of the provided arguments are not string literals or if the pairs don’t have the appropriate structure.