PHP Class $_SERVER Variable a Property

Question

I'm developing a class and I have this structure:

class userInfo {
    public $interval        = 60;
    public $av_langs        = null;

    public $ui_ip           = $_SERVER['REMOTE_ADDR'];
    public $ui_user_agent   = $_SERVER['HTTP_USER_AGENT'];

    public $ui_lang         = null;
    public $ui_country      = null;

    // non-relevant code removed
}

But when executing the script I get this error:

Parse error: syntax error, unexpected T_VARIABLE in D:\web\www\poll\get_user_info\get_user_info.php on line 12

When I changed the 2 $_SERVER vars to simple strings the error disappeared.

So what's the problem with $_SERVER in declaring class properties?

Thanks

The above are not variable assignments, but class property declarations. As such they cannot hold expressions. Not allowed there. You must use constants or do it in the constructor. php.net/manual/en/language.oop5.properties.php — mario
– mario, Commented Aug 8, 2011 at 12:26

Perception · Accepted Answer · 2011-08-09 13:25:32Z

13

Use this code as a guide:

public function __construct() {
    $this->ui_ip = $_SERVER['REMOTE_ADDR'];
    $this->ui_user_agent = $_SERVER['HTTP_USER_AGENT'];
}

edited Aug 9, 2011 at 13:25

Perception

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answered Aug 8, 2011 at 14:08

Chris Whittington

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Comments

user680786 · Accepted Answer · 2011-08-08 12:25:55Z

5

Property can be declared only with value, not expression.
You can create __construct() method, where you can initialize properties in any way.

answered Aug 8, 2011 at 12:25

user680786

3 Comments

medk Over a year ago

ok can you give me a simple example? I'm not very used to classes.

medk Over a year ago

I made simple set_ip() and get_ip() functions and put $ui->set_ip($_SERVER['REMOTE_ADDR']); $ui->get_ip(); and it works, but why not declaring it directly?

user680786 Over a year ago

@medk because $_SERVER['REMOTE_ADDR'] is expression, and expressions are not allowed in that scope (because any expression can be fetched only in runtime). __construct() is "magic" method, where you can initialize all your properties in any way. Read more in manual

Community · Accepted Answer · 2017-05-23 10:28:07Z

3

So what's the problem with $_SERVER in declaring class properties?

You can't preset class properties with variables nor with function calls.

Here is some in-depth discussion on why: Why don't PHP attributes allow functions?

The bottom line however is, it's simply not possible.

edited May 23, 2017 at 10:28

CommunityBot

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answered Aug 8, 2011 at 12:27

Pekka

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