Macro labels

macro_rules! labels {
    (@ { $($out:expr),* $(,)* } $(,)*) => { ... };
    (@ { } $k:expr => $v:expr, $($rest:tt)*) => { ... };
    (@ { $($out:expr),+ } $k:expr => $v:expr, $($rest:tt)*) => { ... };
    ($($args:tt)*) => { ... };
}

Helper macro for generating a set of labels.

While a Label can be generated manually, most users will tend towards the key => value format commonly used for defining hashes/maps in many programming languages. This macro allows users to do the exact same thing in calls that depend on [metrics_core::IntoLabels].

Examples

fn takes_labels<L: IntoLabels>(name: &str, labels: L) {
    println!("name: {} labels: {:?}", name, labels.into_labels());
}

takes_labels("requests_processed", labels!("request_type" => "admin"));