Amp\NullCancellationToken classNullCancellationToken implementsAmp\CancellationToken

A NullCancellationToken can be used to avoid conditionals to check whether a token has been provided.

Instead of writing

if ($token) {

potentially multiple times, it allows writing

$token = $token ?? new NullCancellationToken;

// ...







subscribe —public functionsubscribe(callable$callback):string

Subscribes a new handler to be invoked on a cancellation request.

This handler might be invoked immediately in case the token has already been cancelled. Returned generators will automatically be run as coroutines. Any unhandled exceptions will be throw into the event loop.

Type Parameter Description Default Value
callable $callback Callback to be invoked on a cancellation request. Will receive a `CancelledException` as first argument that may be used to fail the operation's promise. none
unsubscribe —public functionunsubscribe(string$id)

Unsubscribes a previously registered handler.

The handler will no longer be called as long as this method isn't invoked from a subscribed callback.

Type Parameter Description Default Value
string $id No documentation. none
isRequested —public functionisRequested():bool

Returns whether cancellation has been requested yet.

throwIfRequested —public functionthrowIfRequested()

Throws the CancelledException if cancellation has been requested, otherwise does nothing.