Multiple vars assignment in one sentence in PHP

Question

I am asking what could be the consequences of this var assignment definition:

$component = $id = $class = \'\';

I mean is allowed by the ID

Answer 1

This is okay.

PHP uses a copy on write system. It means that with primitive types such as strings or ints are really created in memory on change and will probably be okay in your example.

php

$component = $id = $class = 'foobar';

var_dump($component);
var_dump($id);
var_dump($class);

output

string 'foobar' (length=6)
string 'foobar' (length=6)
string 'foobar' (length=6)

But be careful when you do this with objects, objects are passed by reference and have different behavior:

PHP

class Obj
{
    public $_name;
}

$a = $b = new Obj();
$component = $id = $class = 'foobar';

$b->_name = 'Reynier'; //try to change name of second object only
$id = 'Reynier'; // try to change $id only

var_dump($a);
var_dump($b);

var_dump($component);
var_dump($id);
var_dump($class);

output

#Both object are changed
object(Obj)[1]
  public '_name' => string 'Reynier' (length=7)
object(Obj)[1]
  public '_name' => string 'Reynier' (length=7)

#only $id was changed
string 'foobar' (length=6)
string 'Reynier' (length=6)
string 'foobar' (length=6)