<?php
 
class Email  
{
    public function send()
    {
        echo "E-mail enviado", PHP_EOL;
    }
}
 
class Usuario  
{
    protected $email;
 
    //Injeção de dependência através do método construtor
    public function __construct($email)
    {
        $this->email = $email;
    }
 
    public function porEmail()
    {
        $this->email->send();
    }
}
 
$email = new email();
 
$anunciar = new Usuario($email);
$anunciar->porEmail();

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