Standard Library

class CancelledException

The error delivered to a task that has been cancelled.

since 0.1.0-alpha.1linuxwindowswasm

bases

Exception, ICancelledException

Overview

A cancelled task receives it at its next await, and only there; a task is never interrupted in the middle of running. Its message is task cancelled. It is an ordinary exception: catch it by class or by ICancelledException, or let it end the task. A task group absorbs it when it joins its tasks, so cancellation is not reported as a program error. It is not a RuntimeException.

Examples

try {
    throw CancelledException("stopped");
} catch (RuntimeException e) {
    console.writeln("runtime");
} catch (CancelledException e) {
    console.writeln("cancelled: ${e.message}");
}

cancelled: stopped

Constructors

new

new(string msg)

Creates a cancellation error with a message.

Parameters

msg

The text describing the cancellation.

Examples

CancelledException e = CancelledException("task cancelled");
console.writeln(e.message);

task cancelled

See also

• ICancelledException — The interface of the error that reports that a task was cancelled.
• IException — The interface that every thrown value must implement.