__get和__set魔术方法不可访问

Question

I have a class 'base' and a class 'loader', which looks like this.

class base {

    protected $attributes = Array();   
    public $load = null;           

    function __construct() {

        $this->load = loader::getInstance();  
        echo $this->load->welcome(); //prints Welcome foo
        echo $this->load->name; //prints Foo
        echo $this->name; //doesnt print anything and i want it to print Foo

    }


    public function __get($key) {

        return array_key_exists($key, $this->attributes) ? $this->attributes[$key] : null;
    }

    public function __set($key, $value) {

        $this->attributes[$key] = $value;
    }
}

class loader {

    private static $m_pInstance;       

    private function __construct() {

        $this->name = "Foo";

    }

    public static function getInstance() {
        if (!self::$m_pInstance) {
            self::$m_pInstance = new loader();
        }

        return self::$m_pInstance;
    }

    function welcome() {
        return "welcome Foo";
    }

}

$b = new base();

Now what I want is a way to store variables from loader class and access them from base class using $this->variablename .

How can I achieve this? I don't want to use extends . Any idea ?

Answer 1

I don't feel like you've fully understood what coding the OOP way means. And usually Singletons are code smells so I'll just warn you:

There's probably a better way of accomplish you goal. If you provide more informations we will help you out. In its current form the answer is the following; just remember that I higly discourage its implementation in your code.

Assuming that you want to access only public (and non static) loader 's variables as this->varname in the base class you should just insert this line in the beginning of the base class constructor:

$this->attributes = get_object_vars(loader::getInstance());

This will basically initialize the attributes array with all the loader public vars so that via your __get() method you can access its value.

On a side note, take a look at Dependency Injection design pattern in order to avoid using Singletons.

Answer 2

Your __get/__set methods access $this->attributes but not $this->load .
You could eg do something like (pseudocode)

function __get($key) {
  - if $attribute has an element $key->$value return $attribute[$key] else
  - if $load is an object having a property $key return $load->$key else
  - return null;
}

see also: http://docs.php.net/property_exists

Answer 3

You can make static variable and then you can access this variable from anywhere

public statis $var = NULL;

and you can access it like this

classname::$var;