PHP 静态属性、继承和 self 关键字 [英] PHP Static Properties, Inheritance, and the self keyword

问题描述

这对我来说没有意义:

class A {
    public static $value = "a";
    public static function get_value(){
        return self::$value;
    }
}

echo A::$value;       // a, this makes sense
echo A::get_value();  // a, this makes sense

class B extends A {
    public static $value = "b";
}

echo B::$value;       // b, this makes sense
echo B::get_value();  // a?  :(

为什么self 指针没有按预期工作，类似于this?是否有其他关键字可用于实现此目的?

Why doesn't the self pointer work as expected, similar to this? Is there another keyword that could be used to accomplish this?

如果我将静态函数添加到 B 类，它现在可以按预期工作.

If I add the static function to class B, it now works as expected.

class B extends A {
    public static $value = "b";
    public static function get_value(){
        return self::$value;
    }
}

echo B::get_value();  // b  :)

如果该方法包含超过 1 行，则复制+粘贴此功能并在 2 个位置对其进行管理是没有意义的...

If the method contained more than 1 line, it wouldn't make sense to copy+paste this functionality and manage it in 2 locations...

推荐答案

后期静态绑定:

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

后期静态绑定通过存储在最后一个非转发调用"中命名的类来工作.

late static bindings work by storing the class named in the last "non-forwarding call".

在您的示例中尝试使用 static:: 关键字而不是 self:: .

try using static:: keyword instead of self:: in your example.

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