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

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

define!(PORT: u32 = 1234);

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