Learning some PHP use cases!

Learn.php

 <?php
 
 class Logger {
     public function log( $message ) {
         return "LOG : {$message}" . PHP_EOL;
     }
 }
 
 interface MailSentAction {
     public function sent( $message );
 }
 
 abstract class Mail implements MailSentAction{
     private $logger;
 
     public function __construct( Logger $logger ) {
         $this->logger = $logger;
     }
 
     public function log( $message ) {
         return $this->logger->log( $message );
     }
 
     public function sent( $message ) {
         return $message;
     }
 }
 
 class GoogleMail extends Mail {
     public function send( $message ) {
         return "GoogleMail: {$message}" . PHP_EOL;
     }
 }
 
 class MailgunMail extends Mail{
     public function send( $message ) {
         return "MailgunMail: {$message}" . PHP_EOL;
     }
 }
 
 class UserManager {
     private $mail;
 
     public function __construct( MailSentAction $mail ) {
         $this->mail = $mail;
     }
 
     public function send( $message ) {
         echo $this->mail->send( $message );
     }
 
     public function log( $message ) {
         echo $this->mail->log( $message );
     }
 }
 
 $user_manager = new UserManager();
 $user_manager->send( 'Hello Test' );
 $user_manager->log( 'Log Test' );
 
 $user_manager = new UserManager();
 $user_manager->send( 'Hello Test' );
 $user_manager->log( 'Log Test' );