Context::has

(PHP 8.6+, True Async 1.0)

public Context::has(string|object $key): bool

Checks whether a value with the specified key exists in the current context or in one of the parent contexts. The search is performed up the hierarchy.

Parameters

key: The key to check. Can be a string or an object.

Return Value

true if the key is found in the current or any parent context, false otherwise.

Examples

Example #1 Checking for a key before use

<?php

use function Async\current_context;
use function Async\spawn;

current_context()->set('locale', 'ru_RU');

spawn(function() {
    if (current_context()->has('locale')) {
        $locale = current_context()->find('locale');
        echo "Locale: {$locale}\n"; // "Locale: ru_RU"
    } else {
        echo "Locale not set, using default\n";
    }
});

Example #2 Checking with an object key

<?php

use function Async\current_context;

$cacheKey = new stdClass();

current_context()->set($cacheKey, new RedisCache());

if (current_context()->has($cacheKey)) {
    echo "Cache is available\n";
}

$unknownKey = new stdClass();
var_dump(current_context()->has($unknownKey)); // false

Example #3 Hierarchical check

<?php

use function Async\current_context;
use function Async\spawn;

current_context()->set('global_flag', true);

spawn(function() {
    current_context()->set('local_flag', true);

    spawn(function() {
        var_dump(current_context()->has('global_flag')); // true (from root)
        var_dump(current_context()->has('local_flag'));   // true (from parent)
        var_dump(current_context()->has('unknown'));      // false
    });
});

Documentation