promise.php

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#!/usr/bin/env php
<?php
 
use Sabre\Event\Promise;
use Sabre\Event\Loop;
use function Sabre\Event\coroutine;
 
require __DIR__ . '/../vendor/autoload.php';
 
/* Creating a new promise */
$promise = new Promise();
 
/* After 2 seconds we fulfill it */
Loop\setTimeout(function() use ($promise) {
 
    echo "Step 1\n";
    $promise->fulfill("hello");
 
}, 2);
 
 
/* Callback chain */
 
$result = $promise
    ->then(function($value) {
 
        echo "Step 2\n";
        // Immediately returning a new value.
        return $value . " world";
 
    })
    ->then(function($value) {
 
        echo "Step 3\n";
        // This 'then' returns a new promise which we resolve later.
        $promise = new Promise();
 
        // Resolving after 2 seconds
        Loop\setTimeout(function() use ($promise, $value) {
 
            $promise->fulfill($value . ", how are ya?");
 
        }, 2);
 
        return $promise;
    })
    ->then(function($value) {
 
        echo "Step 4\n";
        // This is the final event handler.
        return $value . " you rock!";
         
    })
    // Making all async calls synchronous by waiting for the final result.
    ->wait();
 
echo $result, "\n";
 
/* Now an identical example, this time with coroutines. */
 
$result = coroutine(function() {
 
    $promise = new Promise();
 
    /* After 2 seconds we fulfill it */
    Loop\setTimeout(function() use ($promise) {
 
        echo "Step 1\n";
        $promise->fulfill("hello");
 
    }, 2);
 
    $value = (yield $promise);
 
    echo "Step 2\n";
    $value .= ' world';
 
    echo "Step 3\n";
    $promise = new Promise();
    Loop\setTimeout(function() use ($promise, $value) {
 
        $promise->fulfill($value . ", how are ya?");
 
    }, 2);
 
    $value = (yield $promise);
 
    echo "Step 4\n";
 
    // This is the final event handler.
    yield $value . " you rock!";
 
})->wait();
 
echo $result, "\n";