PHP Globals access issue when using a variable variable

Question

I have this line in a class function:

$this_value = eval("return $$existing_value;");

This gives me the value I need when the $$existing_value variable is set in the function, but I've found that I actually need to access the global scope in 99% of cases. I've tried rewritting it as $this_value = eval("return global $$existing_value;");, but that returns a php error.

Does any know how I can do this correctly? (by the way, I am aware of the poor pratice this represents - but given the situation I cannot think of any other approaches)

To help people understand the issue better you should probably add a link to the previous question: stackoverflow.com/questions/5065294/… — xzyfer
– xzyfer, Commented Feb 21, 2011 at 12:42

score 2 · Accepted Answer · 2011-02-21 22:32:23Z

2

Try

$this_value = eval('global $existing_value; return $$existing_value;');

or

$this_value = eval('global $$existing_value; return $$existing_value;');

edited Feb 21, 2011 at 22:32

answered Feb 21, 2011 at 12:27

user479911

Sign up to request clarification or add additional context in comments.

3 Comments

YsoL8 Over a year ago

I think the second line would work for single values, but it's choking on the array's I.m searching for. I get a PHP error on an unexpected '[' which is the opening bracket for the array reference.

Poelinca Dorin Over a year ago

i get errors when using double quotes , maybe this will point you in the right direction: ` Parse error: syntax error, unexpected T_LNUMBER in /var/www/index.php(19) : eval()'d code on line 1 Call Stack: 0.0006 645576 1. {main}() /var/www/index.php:0 0.0007 646552 2. sss() /var/www/index.php:22 bool(false) `

user479911 Over a year ago

@YsoL8 I updated my answer. I changed double quotes to single quotes. Did you try it with single quotes instead of double quotes?

Poelinca Dorin · Accepted Answer · 2011-02-21 12:30:52Z

1

$x = 3;

function sss()
{
    $x = 1;
    $y = eval('global $x; return $x;');
    var_dump($y);
}
sss();

Will output int(3) , so it works , but be carefull about double quotes and simple quotes!

answered Feb 21, 2011 at 12:30

Poelinca Dorin

9,7052 gold badges41 silver badges43 bronze badges

Comments

xzyfer · Accepted Answer · 2011-02-21 12:41:44Z

0

Since eval is returning the value you need, you should be bale to just assign the return value to the $_GLOBAL or $_SESSION (preferred because $_GLOBAL is evil) super globals.

$foo['bar'] = "pie";
$fixed_name_variable = "foo['bar']";
$_GLOBAL['foo'] =  eval("return $$fixed_name_variable;");
echo $_GLOBAL['foo']; // pie

answered Feb 21, 2011 at 12:41

xzyfer

14.2k5 gold badges37 silver badges46 bronze badges

1 Comment

YsoL8 Over a year ago

That adds a value to the $_GLOAL array, right? I need to take a value - but see the answer I've given.

YsoL8 · Accepted Answer · 2011-02-21 13:16:41Z

0

I've been re-thinking this process. I have relised that I can add a new array with a fixed name which the various processes contributing to this function can add the values needed, programatically, rather than trying to guess at names.

It'll also be far more secure and reliable than variable variables.

answered Feb 21, 2011 at 13:16

YsoL8

2,2245 gold badges30 silver badges47 bronze badges

Collectives™ on Stack Overflow

PHP Globals access issue when using a variable variable

4 Answers 4

3 Comments

Comments

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

3 Comments

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related