我遇到了以下问题：
<?php
/**
* Mother class defining static methods/attribute
*/
class A
{
public static $_greetings = 'Nothing';
public static function hi()
{
$c = get_called_class();
echo $c.' says '.$c::$_greetings.PHP_EOL;
}
public static function set($classname)
{
$c = get_called_class();
$g = $classname::$_greetings;
echo 'Setting '.$c.'::_greetings to '.$g.PHP_EOL;
$c::$_greetings = $g;
}
}
/**
* Children using inherited static method
*/
class C1 extends A
{
public function say() { self::hi(); }
}
class C2 extends A
{
public function say() { self::hi(); }
}
/**
* Data containers
*/
class D1
{
public static $_greetings = 'Hello World!';
}
class D2
{
public static $_greetings = 'Ola Chica!';
}
// ------------------------------------------------------------------------
/**
* The great misunderstanding...
*/
C1::set( 'D1' );
C2::set( 'D2' );
$c1 = new C1();
$c2 = new C2();
$c1->say();
$c2->say();
echo C1::$_greetings.PHP_EOL;
echo C2::$_greetings.PHP_EOL;
简而言之，A定义了打印静态消息$_greetings的方法。此消息将使用A::set( classname )设置，该也接受包含静态参数$_greetings的类的名称的输入。然后是两个孩子，定义自己的方法say()使用继承的静态hi()打招呼。我希望输出是：
Setting C1::_greetings to Hello World!
Setting C2::_greetings to Ola Chica!
C1 says Hello World!
C2 says Ola Chica!
Hello World!
Ola Chica!
但相反，我得到：
Setting C1::_greetings to Hello World!
Setting C2::_greetings to Ola Chica!
C1 says Ola Chica!
C2 says Ola Chica!
Ola Chica!
Ola Chica!
我想知道为什么...！？提前非常感谢那些花时间了解问题的人:)
我可以在这里找到答案，即使这个问题的措辞方式不同：PHP 5.3：在父类中定义属性时，后期静态绑定不适用于属性，而在子类中缺少属性
在我的小例子中，问题来自这样一个事实，显然，除非另有说明(见下文如何(，静态变量的存储对于类的"家庭"(即，对于母类和所有子类(是相同的。为了确保每个类都有自己的存储，您只需要在子类中重新声明相同的静态变量，如下所示：
/**
* Children using inherited static method
*/
class C1 extends A
{
public static $_greetings;
public function say() { self::hi(); }
}
class C2 extends A
{
public static $_greetings;
public function say() { self::hi(); }
}
将其放回前面的示例，输出完全符合预期：
Setting C1::_greetings to Hello World!
Setting C2::_greetings to Ola Chica!
C1 says Hello World!
C2 says Ola Chica!
Hello World!
Ola Chica!