PHP: Dynamically retrieving global variables - php

Question

I am attempting to write a simple wrapper class to get the value of a global variable. I was thinking to use it like this:
print_r($class->session()->getAll());
print_r($class->cookie()->getAll());
Here's what I have:
class GlobalVars() {
private $current;
public function session() {
$this->current = 'SESSION';
return $this;
}
public function cookie() {
$this->current = 'COOKIE';
return $this;
}
public function getAll() {
return $_{$this->current}; // Obviously wrong
}
public function get($key) {
if (!isset($_{$this->current}[$key])) { // Obviously wrong
return false;
}
return $_{$this->current}[$key]; // Obviously wrong
}
public function set($arr) {
if (is_array($arr)) {
foreach ($arr as $k => $v) {
$_{$this->current}[$k] = $v;
}
}
}
}
$class = new GlobalVars();
print_r($class->session()->getAll());
With this example, I get a Notice: Undefined variable: _ message. What do I need to modify to get this to work?

Answer 1

In my opinion this is just a simple syntactical error you have made. What you did:
public function getAll() {
return $_{$this->current}; // Obviously wrong
}
But the correct way to emulate a variable from string is:
public function getAll() {
return ${"_".$this->current};
}
I have tested it. Similar behaviour for the other variables. More information on variable variables in the docs: http://php.net/manual/en/language.variables.variable.php

Answer 2

It's not gonna work like this. You need variable variables:
$var = "_{$this->current}";
var_dump($$var['rnd']);
Example
It's very bad way to use varVars, because it's not readable and usually IDE does not know what are you using and it's easy to get buggy code.