<?php

class Person {

  protected $name;

  public function __construct($name) {
    $this->name = $name;
  }

  public function getIntroduction() {
    return sprintf(
      'My name is %s',
      $this->name
    );
  }
}

class WorkerPerson extends Person {

  protected $occupation;

  public function __construct($name, $occupation) {

    parent::__construct($name);
    $this->occupation = $occupation;
  }

  public function getIntroduction() {
    return sprintf(
      '%s and my occupation is %s',
      parent::getIntroduction(),
      $this->occupation
    );
  }
}

$person = new Person('Joaquin');
echo $person->getIntroduction();


// This prints "My name is Joaquin"

$worker = new WorkerPerson('Joaquin', 'web development');
echo $worker->getIntroduction();
// This prints "My name is Joaquin and my occupation is web development"