PHP继承和静态方法和属性

Question

Is it safe to say that static properties and methods can not be inherited in PHP? a few examples will be helpful.

Answer 1

No (Apparently I couldn't see the not in the question). public and protected static methods and properties are inherited as you would expect them to be:

<?php
class StackExchange {
    public static $URL;
    protected static $code;
    private static $revenue;

    public static function exchange() {}

    protected static function stack() {}

    private static function overflow() {}
}

class StackOverflow extends StackExchange {
    public static function debug() {
        //Inherited static methods...
        self::exchange(); //Also works
        self::stack();    //Works
        self::overflow(); //But this won't

        //Inherited static properties
        echo self::$URL; //Works
        echo self::$code; //Works
        echo self::$revenue; //Fails
    }
}

StackOverflow::debug();
?>

Static properties and methods obey the visibility and inheritance rules as illustrated in this snippet.