这段代码为何会输出father？-php教程-PHP中文网

这段代码为何会输出father？

php中文网

发布： 2016-06-06 20:33:01

原创

1412人浏览过

<code><?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();
</code>

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回复内容：

<code><?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();
</code>

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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

<code>$son.init(); // son
</code>

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<code>php</code><code><br>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";
    }
}
</code>

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后期静态绑定

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.

<code>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();
</code>

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