Documentation

Coroutine
in package
implements PromiseInterface

Creates a promise that is resolved using a generator that yields values or promises (somewhat similar to C#'s async keyword).

When called, the Coroutine::of method will start an instance of the generator and returns a promise that is fulfilled with its final yielded value.

Control is returned back to the generator when the yielded promise settles. This can lead to less verbose code when doing lots of sequential async calls with minimal processing in between.

use GuzzleHttp\Promise;

function createPromise($value) {
    return new Promise\FulfilledPromise($value);
}

$promise = Promise\Coroutine::of(function () {
    $value = (yield createPromise('a'));
    try {
        $value = (yield createPromise($value . 'b'));
    } catch (\Exception $e) {
        // The promise was rejected.
    }
    yield $value . 'c';
});

// Outputs "abc"
$promise->then(function ($v) { echo $v; });
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Interfaces, Classes and Traits

PromiseInterface
A promise represents the eventual result of an asynchronous operation.

Table of Contents

$currentPromise  : PromiseInterface|null
$generator  : Generator
$result  : Promise
__construct()  : mixed
cancel()  : mixed
Cancels the promise if possible.
getState()  : string
Get the state of the promise ("pending", "rejected", or "fulfilled").
of()  : self
Create a new coroutine.
otherwise()  : PromiseInterface
Appends a rejection handler callback to the promise, and returns a new promise resolving to the return value of the callback if it is called, or to its original fulfillment value if the promise is instead fulfilled.
reject()  : mixed
Reject the promise with the given reason.
resolve()  : mixed
Resolve the promise with the given value.
then()  : PromiseInterface
Appends fulfillment and rejection handlers to the promise, and returns a new promise resolving to the return value of the called handler.
wait()  : mixed
Waits until the promise completes if possible.
nextCoroutine()  : mixed

Properties

Methods

__construct()

public __construct(callable $generatorFn) : mixed
Parameters
$generatorFn : callable
Return values
mixed —

cancel()

Cancels the promise if possible.

public cancel() : mixed
Return values
mixed —

getState()

Get the state of the promise ("pending", "rejected", or "fulfilled").

public getState() : string

The three states can be checked against the constants defined on PromiseInterface: PENDING, FULFILLED, and REJECTED.

Return values
string —

of()

Create a new coroutine.

public static of(callable $generatorFn) : self
Parameters
$generatorFn : callable
Return values
self —

otherwise()

Appends a rejection handler callback to the promise, and returns a new promise resolving to the return value of the callback if it is called, or to its original fulfillment value if the promise is instead fulfilled.

public otherwise(callable $onRejected) : PromiseInterface
Parameters
$onRejected : callable

Invoked when the promise is rejected.

Return values
PromiseInterface —

reject()

Reject the promise with the given reason.

public reject(mixed $reason) : mixed
Parameters
$reason : mixed
Return values
mixed —

resolve()

Resolve the promise with the given value.

public resolve(mixed $value) : mixed
Parameters
$value : mixed
Return values
mixed —

then()

Appends fulfillment and rejection handlers to the promise, and returns a new promise resolving to the return value of the called handler.

public then([callable $onFulfilled = null ][, callable $onRejected = null ]) : PromiseInterface
Parameters
$onFulfilled : callable = null

Invoked when the promise fulfills.

$onRejected : callable = null

Invoked when the promise is rejected.

Return values
PromiseInterface —

wait()

Waits until the promise completes if possible.

public wait([mixed $unwrap = true ]) : mixed

Pass $unwrap as true to unwrap the result of the promise, either returning the resolved value or throwing the rejected exception.

If the promise cannot be waited on, then the promise will be rejected.

Parameters
$unwrap : mixed = true
Return values
mixed —

nextCoroutine()

private nextCoroutine(mixed $yielded) : mixed
Parameters
$yielded : mixed
Return values
mixed —

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