<?php
  

  class father
  

  {
  

  public function __construct()
  

  {
  

  $this->init();
  

  }
  

  

  private function init()
  

  {
  

  echo "father\n";
  

  }
  

  }
  

  

  class son extends father
  

  {
  

  public function __construct(){}
  

  

  public function init()
  

  {
  

  echo "son\n";
  

  }
  

  }
  

  

  $son  = new son();