OneShot class

One-shot channels - Promise-like single-value delivery with advanced semantics.

Specialized channels for delivering exactly one value, similar to futures but with more flexible consumption patterns. Perfect for request-response scenarios, async initialization, and promise-like patterns.

Core Features

  • Single-value semantics: Exactly one value can be sent
  • Flexible consumption: Choose between consume-once or multi-reader patterns
  • Promise-like behavior: Similar to futures but with channel semantics
  • Type-safe results: Explicit success/failure handling
  • Zero buffering: Direct producer-to-consumer handoff

Consumption Modes

consumeOnce: true (Default Promise Behavior)

  • First receiver gets the value and consumes it
  • Channel disconnects immediately after consumption
  • Subsequent receivers get RecvErrorDisconnected
  • Perfect for request-response patterns

consumeOnce: false (Broadcast Promise)

  • All receivers (current and future) get the same value
  • Value remains available until explicitly handled
  • Multiple receivers can read the same result
  • Perfect for initialization values or shared results

Example

import 'dart:async';

import 'package:cross_channel/oneshot.dart';

Future<void> main() async {
  // 1. Create a one-shot promise channel
  // `consumeOnce: true` means only the first receiver gets the value.
  final (responseTx, responseRx) = OneShot.channel<String>(consumeOnce: true);

  // 2. Server Side (Promise resolution)
  unawaited(Future.microtask(() async {
    // Send exactly one response
    await responseTx.send('Operation completed successfully');
  }));

  // 3. Client Side
  final result = await responseRx.recv();

  if (result is RecvOk<String>) {
    print('Response: ${result.value}');
  } else if (result is RecvErrorDisconnected) {
    print('Server disconnected without answering');
  }
}

Constructors

OneShot()

Properties

hashCode → int
The hash code for this object.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited

Static Methods

channel<T>({bool consumeOnce = false, String? metricsId}) → OneShotChannel<T>