PHP中的继承

<?php
class Bar 
{
    private $salary = 3000;

    public $lunch = 1000;

    // php中关于“可见性”的概念
    public function test() {
        $this->testPrivate();
        $this->testPublic();
        echo $this->salary;
        echo $this->lunch;
    }

    // 这个被子类覆盖掉了，这也就解释了结果
    public function testPublic() {
        echo "Bar::testPublic\n";
    }
    
    private function testPrivate() {
        echo "Bar::testPrivate\n";
    }
}

class Foo extends Bar 
{
    // 无法覆盖子类的私有属性
    private $salary = 5000;

    // 覆盖了子类的公有属性
    public $lunch = 2000;

    // 覆盖了子类的公有方法
    public function testPublic() {
        echo "Foo::testPublic\n";
    }
    
    // 无法覆盖
    private function testPrivate() {
        echo "Foo::testPrivate\n";
    }
}

$myFoo = new foo();
$myFoo->test(); 

// Bar::testPrivate 
// Foo::testPublic
?>