php - 这段代码为何会输出father？-PHP中文网问答

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php - 这段代码为何会输出father？

天蓬老师 2017-04-10 15:41:56

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516

<?php
class father
{
    public function __construct()
    {
        $this->init();
    }

    private function init()
    {
        echo "father\n";
    }
}

class son extends father
{
    public function init()
    {
        echo "son\n";
    }
}

$son  = new son();

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全部回复(7)

伊谢尔伦2017-04-10 15:43:56 7楼

因为son里的init方法是public，而father的init方法是private，这个其实表示你son里的init方法并没有重写父类里的方法。那自然调用的仍然是父类自己的实现了

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阿神2017-04-10 15:43:56 6楼

$son.init(); // son

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高洛峰2017-04-10 15:43:56 5楼

php
class father
{
    public function __construct()
    {
        // $this->init();
      static::init();//php5.6
    }

    private function init()
    {
        echo "father\n";
    }
}

class son extends father
{
    /*public function __construct()
    {
        $this->init();
    }*/
    public function init()
    {
        echo "son\n";
    }
}

后期静态绑定

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ringa_lee2017-04-10 15:43:56 4楼

Reference: http://docs.php.net/manual/en/language.oop5.late-static-bindings.php

Note:
In non-static contexts, the called class will be the class of the object instance. Since $this-> will try to call private methods from the same scope, using static:: may give different results. Another difference is that static:: can only refer to static properties.

class father
{
    public function __construct()
    {
        $this->init();
    }

    private function init()
    {
        echo "father\n";
    }
}

class son extends father
{
    public function __construct()
    {
        parent::__construct();
        $this->init();
    }

    private function init()
    {
        echo "son\n";
    }
}

new son();