updating a variable "dynamically"

[janroald]

This one is kind of difficult to explain, but here it goes :

 

Say $_SESSION[a] = 'true'

 

Following url is of course invalid, but constructed to show my intention:

index.php?name_of_variable=$_SESSION[a]&value_to_set=false;

 

Is it possible to send a literal reference to a variable and then evaluate the reference so that i can update the variable without using its name?

[trq]

You could try with variable variables but its not going to work with an array (sessions). My question really though is, why do you need this? Maybe if you explained it a little more we could find another solution.

[janroald]

I'm trying to update session variables through ajax requests.

I want to send the "name" of the variable over url and the value to give it.

 

usual solution is to do a standard :

if($_GET[this]=='that') {

  $that = ...

} else if ...etc

 

But i'm just trying to research the possibility to create a reference to an actual variable based on a string that tells me the variable name.

Create a reference from a variable variable maybe...

 

Sound any less confusing at all? :-) 

 

[trq]

An example that may help.

 

<?php

  session_start();
  $_SESSION['that'] = 'bar';
  echo $_SESSION['that'].'<br />';
  if (isset($_GET['this'])) { // pass a url like ?this=that&val=foo
    if (isset($_GET['val'])) {
      $_SESSION[$_GET['this']] = $_GET['val'];
    }
  }
  echo $_SESSION['that'];

?>

[janroald]

No, not that easy :-)

forget sessions, think just a simple variable

 

$foo = 'bar';

 

// pass a url like ?this=foo&value=foobar

 

How can i now, if at all possible, use $_GET[this] to create a reference to $foo and update it so that

 

echo $foo; //foobar

[trq]

Yeah... I don't think its possible as variable variable will not work with the superglobals.

[janroald]

Better example of what i'm trying to do. (of course, this dont work)

// pass a url like ?this=foo&value=foobar

$foo = 1;

eval("\$bar =& \$$_GET[this];")

$bar = 2;

echo $foo; //2

 

Had a feeling this was a dead end, but had to try :-)