interfaceInjection.php

<?php
interface questionInterface{
  public function setAuthor(Author $author);
}
class Question implements questionInterface {
    private $author;
    private $question;
 
    public function __construct($question) {
        $this->question = $question;
    }
    
    public function setAuthor(Author $author) {
      $this->author = $author;
    }
    
    public function getAuthor() {
        return $this->author;
    }
 
    public function getQuestion() {
        return $this->question;
    }
}
?>