Struct SampleOrKey

Source

pub struct SampleOrKey<T>where
    T: Topicable,
{ /* private fields */ }

Expand description

A received sample, which is either a full payload of type T or a key-only payload carrying T::Key.

Key-only samples are produced when an instance is disposed or unregistered by a writer. SampleOrKey derefs to T in both cases: for key-only samples this materializes a default T from the key via Topicable::from_key.

Use view to distinguish between the two cases without triggering materialisation.

Implementations§

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impl<T> SampleOrKey<T>
where T: Topicable,

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pub const fn info(&self) -> &Info

Returns the metadata associated with this sample.

§Examples

let sample = &reader.take()?[0];
let info = sample.info();
println!("source timestamp: {:?}", info.source_timestamp);

Source

pub fn sample(&self) -> Option<&T>

Returns a reference to the full sample payload, or None if this is a key-only sample.

§Examples

let sample = &reader.take()?[0];
if let Some(data) = sample.sample() {
    println!("payload: {data:?}");
}

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pub fn into_sample(self) -> Option<T>

Consumes self and returns the full sample payload, or None if this is a key-only sample.

§Examples

let sample = reader.take()?.into_iter().next().unwrap();
if let Some(data) = sample.into_sample() {
    println!("payload: {data:?}");
}

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pub const fn is_sample(&self) -> bool

Returns true if this is a full sample.

§Examples

let sample = reader.take()?.into_iter().next().unwrap();
assert!(sample.is_sample());

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pub fn is_sample_and(&self, f: impl FnOnce(&T) -> bool) -> bool

Returns true if this is a full sample and f returns true for its payload.

§Examples

let sample = reader.take()?.into_iter().next().unwrap();
assert!(sample.is_sample_and(|data| data.x == 0));

Source

pub fn key(&self) -> Option<&T::Key>

Returns a reference to the instance key, or None if this is a full sample.

§Examples

let sample = reader.take()?.into_iter().next().unwrap();
if let Some(key) = sample.key() {
    println!("key-only notification: {key:?}");
}

Source

pub fn into_key(self) -> Option<T::Key>

Consumes self and returns the instance key, or None if this is a full sample.

§Examples

let sample = reader.take()?.into_iter().next().unwrap();
if let Some(key) = sample.into_key() {
    println!("key-only notification: {key:?}");
}

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pub const fn is_key(&self) -> bool

Returns true if this is a key-only sample.

§Examples

let sample = reader.take()?.into_iter().next().unwrap();
assert!(!sample.is_key());

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pub fn is_key_and(&self, f: impl FnOnce(&T::Key) -> bool) -> bool

Returns true if this is a key-only sample and f returns true for its key.

§Examples

let sample = reader.take()?.into_iter().next().unwrap();
assert!(!sample.is_key_and(|key| key.x == 1));

Source

pub fn view(&self) -> View<'_, T>

Returns a borrowed View of this sample for pattern matching without triggering key or sample materialisation.

§Examples

use cyclonedds::sample::View;

for sample in reader.take()? {
    match sample.view() {
        View::Sample(data) => println!("sample: {data:?}"),
        View::Key(key) => println!("key-only: {key:?}"),
    }
}