interface EmailMaker
{
    public function makeEmailHTML(): string;
}
class EmailSender
{
    private $emails;
    
    public function addEmail($address, EmailMaker $emailMaker)
    {
        $email = [
            'address' => $address,
            'emailHTML' => $emailMaker->makeEmailHTML(),
        ];
        array_push($this->emails, $email);
    }
    public function getEmails(){
        return $this->emails;
    }
}
$emails=new EmailSender();
$emails->addEmail('test','');
print_r($emails->getEmails());

目前正在練習物件導向的多型參考了範例想請大家幫忙解惑,

問題1:當介面已設定一個EmailMaker的介面,再addEmail參數中使用了
EmailMaker $emailMaker 請問這是甚麼用法?

問題2:interface要實現如果沒有implements 是如何可以使用的?

問題3:當addEmail宣告EmailMaker $emailMaker 的參數時,如何再建立物件後怎麼使用?

題外話對於多型和里氏替換原則倆著之間有甚麼使用時機嗎(歡迎大家跟小弟分享謝謝)~仍然學習的路上

如有問得不好的地方請鞭小力點~