🔗 SOLID Principles

A class should have one and only one reason to change, meaning that a class should have only one job.

Let’s take the example that I have a Messenger class:

class Messenger extends SomeBasicMessenger {

	public function sendMessage(Message $message) {
		$result = $this->getBus()->send($message);
		$this->logResult($result);
	}

	protected function logResult(Result $result) {
		file_put_content(__DIR__ . md5(time()).'.log', $result->getMessage());
	}

}

The problem with is, of course, is the fact that the class handles both sending a message and logging the result of the message. It is far better practice to dependency inject a dedicated Logger and delegate the logging to that class.

Let’s say the Logger class writes into a log file on the server disk, as in the example. If multiple classes use that Logger class, I can decide to store the logs in the database instead and have all logging classes implement that behaviour.