Question

Why can’t I set $_SERVER['DOCUMENT_ROOT'] as attribute?
see example code

class foo
{
private $path = $_SERVER['DOCUMENT_ROOT']; // generates error
private $blah;

public function __construct()
{
//code
}

  public function setBla($bla)
  {
   $this->blah = $bla;

  }
}

Answer 1

you cannot use other variable when initializing in declaration. try this:

class foo
{
private $path;
private $blah;

public function __construct()
{
$this->$path = $_SERVER['DOCUMENT_ROOT'];
//code
}

  public function setBla($bla)
  {
   $this->blah = $bla;

  }
}

by the way, are you sure private is an appropriate choice, often protected is preferable.