Promise

An implementation of the Promise pattern.

A promise represents the result of an asynchronous operation. At any given point a promise can be in one of three states:

Pending (the promise does not have a result yet).
Fulfilled (the asynchronous operation has completed with a result).
Rejected (the asynchronous operation has completed with an error).

To get a callback when the operation has finished, use the then method.

Full name: \Sabre\Event\Promise

Constants

Constant	Visibility	Value
`PENDING`	public	0
`FULFILLED`	public	1
`REJECTED`	public	2

Properties

state

The current state of this promise.

public int $state

subscribers

A list of subscribers. Subscribers are the callbacks that want us to let them know if the callback was fulfilled or rejected.

protected array $subscribers

value

The result of the promise.

protected mixed $value

If the promise was fulfilled, this will be the result value. If the promise was rejected, this property hold the rejection reason.

Methods

__construct

Creates the promise.

public __construct(callable $executor = null): mixed

The passed argument is the executor. The executor is automatically called with two arguments.

Each are callbacks that map to $this->fulfill and $this->reject. Using the executor is optional.

Parameters:

Parameter	Type	Description
`$executor`	callable

then

This method allows you to specify the callback that will be called after the promise has been fulfilled or rejected.

public then(callable $onFulfilled = null, callable $onRejected = null): \Sabre\Event\Promise

Both arguments are optional.

This method returns a new promise, which can be used for chaining. If either the onFulfilled or onRejected callback is called, you may return a result from this callback.

If the result of this callback is yet another promise, the result of that promise will be used to set the result of the returned promise.

If either of the callbacks return any other value, the returned promise is automatically fulfilled with that value.

If either of the callbacks throw an exception, the returned promise will be rejected and the exception will be passed back.

Parameters:

Parameter	Type	Description
`$onFulfilled`	callable
`$onRejected`	callable

otherwise

Add a callback for when this promise is rejected.

public otherwise(callable $onRejected): \Sabre\Event\Promise

Its usage is identical to then(). However, the otherwise() function is preferred.

Parameters:

Parameter	Type	Description
`$onRejected`	callable

fulfill

Marks this promise as fulfilled and sets its return value.

public fulfill(mixed $value = null): mixed

Parameters:

Parameter	Type	Description
`$value`	mixed

reject

Marks this promise as rejected, and set its rejection reason.

public reject(\Throwable $reason): mixed

Parameters:

Parameter	Type	Description
`$reason`	\Throwable

wait

Stops execution until this promise is resolved.

public wait(): mixed

This method stops execution completely. If the promise is successful with a value, this method will return this value. If the promise was rejected, this method will throw an exception.

This effectively turns the asynchronous operation into a synchronous one. In PHP it might be useful to call this on the last promise in a chain.

invokeCallback

This method is used to call either an onFulfilled or onRejected callback.

private invokeCallback(\Sabre\Event\Promise $subPromise, callable $callBack = null): mixed

This method makes sure that the result of these callbacks are handled correctly, and any chained promises are also correctly fulfilled or rejected.

Parameters:

Parameter	Type	Description
`$subPromise`	\Sabre\Event\Promise
`$callBack`	callable

Automatically generated on 2025-03-18