Macro attributes

macro_rules! attributes {
    (@ { $(,)* $($val:expr),* $(,)* }, $(,)*) => { ... };
    (@ { $(,)* $($out:expr),* }, $($key:ident).+, $($rest:tt)+) => { ... };
    (@ { $(,)* $($out:expr),* }, $($key:ident)+ = $value:expr, $($rest:tt)+) => { ... };
    (@ { $(,)* $($out:expr),* }, $key:literal = $value:expr, $($rest:tt)+) => { ... };
    (@ { $(,)* $($out:expr),* }, $($key:ident).+) => { ... };
    (@ { $(,)* $($out:expr),* }, $($key:ident)+ = $value:expr) => { ... };
    (@ { $(,)* $($out:expr),* }, $key:literal = $value:expr) => { ... };
    ({ $($kvs:tt)+ }) => { ... };
    ($($kvs:tt)+) => { ... };
    ($(,)?) => { ... };
}

Constructs a slice of KeyValue attributes.

This macro is primarily used when manually constructing spans, such as root spans that don’t have a convenience macro.

Syntax

The macro supports several attribute formats:

• identifier = value - Uses the identifier as the key name
• "literal" = value - Uses the literal string as the key name
• identifier - Uses the identifier as both key and value
• field.subfield - Simple dot notation for field access

Examples

Basic usage with mixed attribute types:

use veecle_telemetry::attributes;

let user_id = 123;
let service_name = "auth-service";
let attrs = attributes!(user_id = user_id, "service" = service_name, "version" = "1.0.0");

Using identifiers as both key and value:

use veecle_telemetry::attributes;

let database = "postgresql";
let timeout = 30;
let attrs = attributes!(
    database, // equivalent to database = database
    timeout = timeout,
    "connection_pool" = "primary"
);

Root span construction with attributes:

use veecle_telemetry::{Span, SpanContext, attributes};

let operation = "user_login";
let user_id = 456;
let span = Span::root(
    "authentication",
    SpanContext::generate(),
    attributes!(operation = operation, user_id = user_id, "security_level" = "high"),
);

Empty attributes:

use veecle_telemetry::attributes;
use veecle_telemetry::value::KeyValue;

let attrs: &[KeyValue] = attributes!(); // Creates an empty slice