<?php
abstract class Animal
{
    protected $name;
    public function run()
    {
        echo 'Aniaml run';
        $this->swim();
        echo $this->fishNum;

    }
}

class Fish extends Animal
{
   public $fishNum=10;
    public function swim()
    {
        echo 'Fish swim';
    }
}
$fish=new Fish();
$fish->swim();
$fish->run();

class A {
    private $b;
    function __construct($a){
        $this->b = $a;
    }
    function func1(){
        var_dump($this->b);
    }
    function func2(){
        $this->funcb();
    }
}

class B extends A {
    function funcb(){
        var_dump("b");
    }
}

$a = new B('a');
$a->func1();
$a->func2();