Trait EventSink

Source

pub trait EventSink {
    // Required method
    fn emit(&mut self, event: RunEvent);

    // Provided methods
    fn delta(&mut self, node: &str, text: &str) { ... }
    fn settled(&mut self, node: &str, kept: bool) { ... }
}

Expand description

Where a run’s observable output goes.

Two channels, and the difference between them is the point.

emit carries the event stream: the record of what the run did. It is ordered, it is timestamp-free, and replaying a cassette reproduces it byte for byte, which is what lets a test assert on it.

delta and settled carry the live channel: text as a model produces it. None of it is a record of anything. How an answer arrived over the wire is a property of the connection, not of the run, so a delta is never an event, never recorded in a cassette, and never asserted on. Both default to discarding, so a sink that only wants the record gets exactly the record.

Required Methods§

Source

fn emit(&mut self, event: RunEvent)

Provided Methods§

Source

fn delta(&mut self, node: &str, text: &str)

A fragment of a model’s answer, as it arrives.

Called only on a live call against a provider that streams. Fragments for one node arrive in order and concatenate to the answer’s text; a watcher that shows them is showing something that may yet be thrown away, which is what settled is for.

Source

fn settled(&mut self, node: &str, kept: bool)

No more deltas for this node, and whether the text became the answer.

kept is false when the response was discarded — the answer was cut off, or it did not match its declared type — so a watcher can strike what it showed instead of leaving a half-finished answer on screen looking like a result. Called only after at least one delta.