Context::set

(PHP 8.6+, True Async 1.0)

public Context::set(string|object $key, mixed $value, bool $replace = false): Context

Sets a value in the current context with the specified key. By default, if the key already exists, the value is not overwritten. To force overwriting, use the replace = true parameter.

The method returns the Context object, allowing method chaining.

Parameters

key: The key to set the value for. Can be a string or an object. Object keys are useful for avoiding name conflicts between libraries.
value: The value to store. Can be of any type.
replace: If false (default) — do not overwrite an existing value. If true — overwrite the value even if the key already exists.

Return Value

The Context object for method chaining.

Examples

Example #1 Setting values with string keys

<?php

use function Async\current_context;

// Method chaining
current_context()
    ->set('request_id', 'req-001')
    ->set('user_id', 42)
    ->set('locale', 'ru_RU');

echo current_context()->find('request_id') . "\n"; // "req-001"
echo current_context()->find('user_id') . "\n";    // 42

Example #2 Behavior without overwriting

<?php

use function Async\current_context;

current_context()->set('mode', 'production');

// Setting again without replace — value does NOT change
current_context()->set('mode', 'debug');
echo current_context()->find('mode') . "\n"; // "production"

// With replace = true — value is overwritten
current_context()->set('mode', 'debug', replace: true);
echo current_context()->find('mode') . "\n"; // "debug"

Example #3 Object keys for library isolation

<?php

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

// Each library uses its own object key
class LoggerContext {
    public static object $key;
}
LoggerContext::$key = new stdClass();

class CacheContext {
    public static object $key;
}
CacheContext::$key = new stdClass();

current_context()
    ->set(LoggerContext::$key, new FileLogger('/var/log/app.log'))
    ->set(CacheContext::$key, new RedisCache('localhost:6379'));

spawn(function() {
    $logger = current_context()->find(LoggerContext::$key);
    $cache = current_context()->find(CacheContext::$key);

    $logger->info('Cache initialized');
});

Example #4 Passing context to child coroutines

<?php

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

// Parent context
current_context()
    ->set('trace_id', bin2hex(random_bytes(8)))
    ->set('service', 'api-gateway');

// Child coroutines inherit values through find()
spawn(function() {
    $traceId = current_context()->find('trace_id');
    echo "Processing request: {$traceId}\n";

    // Child coroutine adds its own value
    current_context()->set('handler', 'user_controller');
});

Documentation