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Coroutine.md

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Coroutine

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; });
  • Full name: \GuzzleHttp\Promise\Coroutine
  • This class is marked as final and can't be subclassed
  • This class implements: \GuzzleHttp\Promise\PromiseInterface
  • This class is a Final class

See Also:

Properties

currentPromise

private \GuzzleHttp\Promise\PromiseInterface|null $currentPromise

generator

private \Generator $generator

result

private \GuzzleHttp\Promise\Promise $result

Methods

__construct

public __construct(callable $generatorFn): mixed

Parameters:

Parameter Type Description
$generatorFn callable

of

Create a new coroutine.

public static of(callable $generatorFn): self
  • This method is static.

Parameters:

Parameter Type Description
$generatorFn callable

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): \GuzzleHttp\Promise\PromiseInterface

Parameters:

Parameter Type Description
$onFulfilled callable Invoked when the promise fulfills.
$onRejected callable Invoked when the promise is rejected.

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): \GuzzleHttp\Promise\PromiseInterface

Parameters:

Parameter Type Description
$onRejected callable Invoked when the promise is rejected.

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:

Parameter Type Description
$unwrap 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.

resolve

Resolve the promise with the given value.

public resolve(mixed $value): mixed

Parameters:

Parameter Type Description
$value mixed

reject

Reject the promise with the given reason.

public reject(mixed $reason): mixed

Parameters:

Parameter Type Description
$reason mixed

cancel

Cancels the promise if possible.

public cancel(): mixed

nextCoroutine

private nextCoroutine(mixed $yielded): mixed

Parameters:

Parameter Type Description
$yielded mixed