Macro topic

macro_rules! topic {
    ($tyname:ident, $msg:tt $(< $msg_lt:lifetime >)? $(,)?) => { ... };
    ($tyname:ident, $msg:tt $(< $msg_lt:lifetime >)?, $path:expr $(,)?) => { ... };
}

Topic macro

Used to define a single Topic marker type that implements the Topic trait.

Borrowed types may contain lifetimes, but only as types with lifetimes, not direct references. This means we can accept Borrowed<'a> as a type but not &'a str.

use ergot::topic;

#[derive(Schema, Debug, PartialEq, Serialize, Deserialize)]
pub struct Stir<'a> {
    s: &'a str,
}

#[derive(Debug, Serialize, Deserialize, Schema)]
pub struct Message1 {
    a: u8,
    b: u64,
}

// owned topic
topic!(Topic1, Message1, "topic/1");

// borrowed topic
topic!(Topic2, Stir<'a>, "topic/2");

If the path is omitted, the type name is used instead.