Mastering PHP 7

Subject

Rx\Subject\Subject is an interesting component--it's a class that acts both as observable and observer. The benefit of this is seen in the following example:

use \Rx\Subject\Subject;$mailer = new class() extends Subject{    public function onCompleted()    {        echo 'mailer.onCompleted', PHP_EOL;        parent::onCompleted();    }    public function onNext($val)    {        echo 'mailer.onNext: ', $val, PHP_EOL;        parent::onNext($val);    }    public function onError(\Throwable $error)    {        echo 'mailer.onError', $error->getMessage(), PHP_EOL;        parent::onError($error);    }};$logger = new class() extends Subject{    public function onCompleted()    {        echo 'logger.onCompleted', PHP_EOL;        parent::onCompleted();    }    public function onNext($val)    {        echo 'logger.onNext: ', $val, PHP_EOL;