pub struct DefaultParam<T> {
    value: T,
    name: &'static str,
}

macro_rules! define {
    ( $name:ident, $val:expr, $t:ty ) => {
        pub const $name: DefaultParam<$t> = DefaultParam {
            value: $val,
            name: stringify!($val),
        };
    }
}

define!(PORT, 1234, u32);

fn main() {
    println!("{} has the value: {}", PORT.name, PORT.value);
}