Php 包含的脚本不读取相同的 static 变量？

Question

i am having a problem with calling static variables/methods between classes through an included file.

that's code example:

<?php

class Router
{
    static $instance;

    public static function GetInstance()
    {
        if(self::$instance == null)
            self::$instance = new self;

        return self::$instance;
    }

    function __construct()
    {

        include 'test2.php';

        /*  test2.php CONTENTS          */
        /*  Routes::doSomething();      */
    }


    public function doSomthing()
    {
        echo 1;
    }
}

class Routes
{
    // test.php script will call this function
    // this function will try to get Router static instance to call a dynamic function
    // keep in mind that the static instance of Router was already created
    // some how test2.php script will not be able to read the static instance and will create another one
    // and that will cause the page keep including and running the same script over and over and idk why
    public static function doSomething()
    {
        Router::GetInstance()->doSomthing();
    }

}

$router = Router::GetInstance();

where the script Routes::doSomething(); in test2.php will not be able to read the static $instance in Router class.

i can't figure out what's the problem and tried to look if including scripts will cause such issue but i don't even know what i should look for.

help please, thanks.

Answer 1

After some tests turn out PHP cannot handle such script. Because of the process of declaring variables and how PHP handle it.

There's no source that i can give to support what i am about to say, its only what i understood so far from my tests. But i will try to explain it with my low English level hoping that might help someone sometime later.

So in PHP when you try to declare a static/dynamic variable with class object like this:

self::$Instance = new TestClass;

Php will process the command in steps to work in this way:

Step#1: Declare self::$Instance as null

Step#2: Create temporary_object from TestClass class

step#3: Run __construct method in temporary_object then wait until its done

Step#4: Set self::$Instance as temporary_object which is instanceof TestClass

The problem in my code as you can see that i was trying to include .php file inside of __construct method. The included file will run a static function that will try to read self::$instance in Router class. While static::$Instance is not set and still equal null because __construct isn't done yet.

So basically don't try to read static instance of the same class inside __construct method.

And here how the script should be, in cause my explanation was not clear:

<?php

class Router
{
    static $instance;

    public static function GetInstance()
    {
        if(self::$instance == null)
            self::$instance = new self;

        return self::$instance;
    }

    function __construct()
    {

    }

    public function LoadFiles(){
        
        include 'test2.php';

        /*  test2.php CONTENTS          */
        /*  Routes::doSomething();      */
    }

    public function doSomthing()
    {
        echo 1;
    }
}

class Routes
{
    // test.php script will call this function
    // this function will try to get Router static instance to call a dynamic function
    // keep in mind that the static instance of Router was already created
    // some how test2.php script will not be able to read the static instance and will create another one
    // and that will cause the page keep including and running the same script over and over and idk why
    public static function doSomething()
    {
        Router::GetInstance()->doSomthing();
    }

}

$router = Router::GetInstance();
$router->LoadFiles();