标签:php inheritance static-members
我有两个类(模型和用户),但我有一个问题所以我试图在一个简单的例子中解释它:
class person
{
protected static $todo ="nothing";
public function __construct(){}
public function get_what_todo()
{
echo self::$todo;
}
}
class student extends person
{
protected static $todo ="studing";
}
$s = new student();
$s->get_what_todo(); // this will show the word (nothing)
//but I want to show the word (studing)
请给我一个解决方案,但没有在学生班写任何功能我只想在那里做声明:)谢谢:)
解决方法:
该原则称为“late static binding”,并在PHP 5.3.0中引入;使用self关键字访问继承树中调用类中定义的属性,或使用static访问该继承树中子类中定义的属性.
class person
{
protected static $todo ="nothing";
public function __construct(){}
public function get_what_todo()
{
echo static::$todo; // change self:: to static::
}
}
class student extends person
{
protected static $todo ="studying";
}
class teacher extends person
{
protected static $todo ="marking";
}
class guest extends person
{
}
$s = new student();
$s->get_what_todo(); // this will show the "studying" from the instantiated child class
$t = new teacher();
$t->get_what_todo(); // this will show the "marking" from the instantiated child class
$g = new guest();
$g->get_what_todo(); // this will show the "nothing" from the parent class,
// because there is no override in the child class
标签:php,inheritance,static-members 来源: https://codeday.me/bug/20190716/1475413.html
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