pattern1.php

<?php

declare(strict_types=1);

class a
{
    /** @var string */
    private static $foo;
    
    public static function getFoo(): string
    {
        return self::$foo;
    }
    
    public function __construct()
    {
        self::$foo = "hoge!";
    }
}

class b
{
    public function __construct()
    {
        echo a::getFoo() . PHP_EOL;//hoge!
    }
}

pattern2.php

<?php

declare(strict_types=1);

class a
{
    public function hoge(): void
    {
        $foo = "fuga!";
        new b($foo);
    }
}

class b
{
    public function __construct(string $foo)
    {
        echo $foo . PHP_EOL;//fuga!
    }
}

pattern3.php

<?php

declare(strict_types=1);

class DataManager
{
    public static $foo;
}

class EventListener
{
    public function __construct()
    {
        DataManager::$foo = "piyo";
    }
}

class FooCommand
{
    public function __construct()
    {
        DataManager::$foo = "aaaaa";
    }
    
    public function command(): void
    {
        echo DataManager::$foo;
    }
}