completed

Whether the task has completed, meaning its callback (if set) has been invoked.

This can only happen after return_pointer, return_error or one of the other return functions have been called on the task. However, it is not guaranteed to happen immediately after those functions are called, as the task’s callback may need to be scheduled to run in a different thread.

That means it is **not safe** to use this property to track whether a return function has been called on the Task. Callers must do that tracking themselves, typically by linking the lifetime of the Task to the control flow of their code.

This property is guaranteed to change from false to true exactly once.

The notify signal for this change is emitted in the same main context as the task’s callback, immediately after that callback is invoked.