PHP Class: Global Variable as Property in Class

PHP class: Global variable as property in class

You probably don't really want to be doing this, as it's going to be a nightmare to debug, but it seems to be possible. The key is the part where you assign by reference in the constructor.

$GLOBALS = array(
    'MyNumber' => 1
);

class Foo {
    protected $glob;

    public function __construct() {
        global $GLOBALS;
        $this->glob =& $GLOBALS;
    }

    public function getGlob() {
        return $this->glob['MyNumber'];
    }
}

$f = new Foo;

echo $f->getGlob() . "\n";
$GLOBALS['MyNumber'] = 2;
echo $f->getGlob() . "\n";

The output will be

1
2

which indicates that it's being assigned by reference, not value.

As I said, it will be a nightmare to debug, so you really shouldn't do this. Have a read through the wikipedia article on encapsulation; basically, your object should ideally manage its own data and the methods in which that data is modified; even public properties are generally, IMHO, a bad idea.

PHP use global variables in class/object

The right way would be to use a constructor - a method that will run when the object is created.

When you define class properties, you can only use constant values (1, 'xyz', array() are fine for example), not expressions that need to be evaluated at runtime.

Pass the variable to the constructor, and don't use global variables.

class myObject {
    public $username;
    public $zzz;

    public function __construct($variable) {
        $this->username = $variable + 5 ;
        $this->zzz = $this->username + 5;
    }
}

$obj = new myObject(10);
echo $obj->username; //15

In PHP, you don't need to use classes and objects if you don't want to write OOP code. You can simply create good old functions. But if you want to use them, try to get familiar with OOP concepts.

How do declare global variable in PHP class

First up, you're not trying to create a "global variable" (as your title suggests), but a private member variable.

In order to do that you need to declare the private member variable outside of the constructor:

class Auth extends Controller {

    private $pass;

    function __construct(){
    }

    function auth()
    {
        parent::Controller();   
        $this->load->library('session');
        $this->load->helper('cookie');
        $this->load->library('email');
    }
    function index(){
            ..........
    }
    function loging(){
        $this->pass = "Hello World";
    }
    function test(){
        echo $this->pass;
    }
}

Also:

• Correct the name of your constructor
• Chose a naming convention (e.g. lowercase first character of function names) and stick to it.

As a trivial answer / example of what you are asking. Try this:

<?php

    class Auth {

        private $pass;

        function __construct(){
        }

        function loging(){
            $this->pass = "Hello World";
        }
        function test(){
            echo $this->pass;
        }
    }

    $oAuth = new Auth();
    $oAuth->loging();
    $oAuth->test();

?>

It outputs:

C:\>php test.php
Hello World

How to use the global variable to initialize the class property?

To access a global variable you need to use the global variable with global keyword, Secondly your modifier and class shares the same name which afaik will confuse the compiler see the below snippet

Nope It doesn't

   <?php

$str = <<<EOD
Example of string
spanning multiple lines
using heredoc syntax.
EOD;

class foo
{
    public  $foo;

    function __construct()
    {
        global $str;
        $this->foo = $str;
    }

}

$foo = new foo();
echo $foo->foo;
?>

Snippet

Why not to use global variables

Class Property Containing a Global Variable

Figured it out, used a solution to solve my problem from another question:

PHP class: Global variable as property in class

PHP: set a global variable in a class

You can declare $settings as a class property

protected $settings;

Then inside __construct

$this->settings = get_option( 'my_options' );

You can then access it anywhere inside the class using $this->settings

public function function_1() {
    echo 'This option is ' . $this->settings['option_1'];
}

For more details about properties, you can refer to PHP documentation http://php.net/manual/en/language.oop5.properties.php

How to pass Global variables to classes in PHP?

Well, you can declare a member variable, and pass it to the constructor:

class Administrator {
    protected $admin = '';

    public function __construct($admin) {
        $this->admin = $admin;
    }

    public function logout() {
        $this->admin; //That's how you access it
    }
}

Then instantiate by:

$adminObject = new Administrator($admin);

But I'd suggest trying to avoid the global variables as much as possible. They will make your code much harder to read and debug. By doing something like above (passing it to the constructor of a class), you improve it greatly...

Access global variables and static class properties of another file, without bringing those into scope

My solution here was to create a version of my “sub-subject” code that, instead of echo’ing HTML, echo’ed a JSON of the variables I was interested in with json_encode.

Then the other file used json_decode(`php sub-subject-json.php`);. The backtick operator executes a shell command, in this case, php itself called with the file I want to look at.

So, for example, where previously I might have had

minion.php

<?php
  $name = 'Steve';
  $attack = 3;
  $damage = '1d6+3';
?><!DOCTYPE html>
<html>
<head><title><?php echo $name; ?></title></head>
<body>
  <h1><?php echo $name; ?></h1>
  <p><?php echo formatBonus($attack) . " $damage"; ?>
</body>
</html>

Now I have

minion-core.php

<?php
  $name = 'Steve';
  $attack = 3;
  $damage = '1d6+3';
?>

minion.php

<?php require_once('minion-core.php'); ?><!DOCTYPE html>
<html>
<head><title><?php echo $name; ?></title></head>
<body>
  <h1><?php echo $name; ?></h1>
  <p><?php echo formatBonus($attack) . " $damage"; ?>
</body>
</html>

minion-json.php

<?php
  require_once('minion-core.php');
  header('Content-Type: application/json; charset=utf-8');
  echo json_encode([
    'name' => $name,
    'attack' => $attack,
    'damage' => $damage,
  ]);
?>

And then my main file can include

leader.php

$steve = json_decode(`php minion-json.php`);

This is a nasty, ugly hack. But it does work, and it works without refactoring everything I’ve written.

PHP global variable inside a class

Use static variables if you want them to have one and the same value, available regardless of their class instances (tutorial):

class bla
{
    private static $x;

    public function setx($x) {
        self::$x = $x;
    }

    public function getx() {
        return self::$x;
    }
}

$object1 = new bla();
$object1->setx(5);
echo $object1->getx();
echo '<br>';

$object2 = new bla();
echo $object2->getx();

Output:

5
5

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