PHP - Best Practice for Passing Variables to Include Files

Question

This is more of a 'How should I?' rather than 'How do I?' question.

Generally, what is considered the best way to pass variables to an included file?

For example, let's say I'm using a fragment for a menu, and want one of the menu items (the current one) to have a certain class name (this is a very generic sample - not something I'm actually using):

<?php
$links = array(
    array('text' => 'home', 'href' => 'home.php'),
    array('text' => 'about', 'href' => 'about.php'),
    array('text' => 'contact', 'href' => 'contact.php') 
);
?>
<ul>
<?php for($i = 0; $i < 3; $i++) : 
    $link = $links[$i];
    $is_active = ($i == $active_index);
?>
    <li><a <?=($is_active ? 'class="active"' : '')?> href="<?=$link['href']?>"><?=$link['text']?></a></li>
<?php endfor; ?>
</ul>

i'll call the above 'menu.inc.php'. obviously it's looking for a variable (int) called $active_index to determine which link to give the '.active' class to.

so - you could just define $active_index before calling the include, but this seems like poor practice to me since perhaps a variable of that name might have been defined for something else earlier and a later part of the script is still looking for it.

or - you could use an absolute path and append variables using a querystring (include 'menu.inc.php?active_index=1'), but again that seems like a bad idea since you might need the 'real' $_GET within any given include.

or - you could start each included file with ob_start and return ob_end_clean(), then use something like this to get the return:

function load_view($file, $variables){
  extract($variables);
  return include($file);
}
// passed like
<?=load_view('menu.inc.php', array('active_index' => 2))?>

but again this seems to have a number of cons (having to restructure all your include files accordingly with the ob functions and a return statement).

Answer 1

I like an object for this, as described in this MVC stack post. In a file called viewMenu.class.php,

class viewMenu
  {
  private $active_link;

  public function __construct ( $active_link )
    {
    $this->active_link = $active_link; 
    }
  //If the constructor doesn't work for you, try a "set" method.  

  public function view ()
    {
    $active_link = $this->active_link;
    include_once ( "menu.inc.php" );
    }
  }

Defining $active_link inside the view method contains the variable scope of $active_link to within the method. Then call this code:

$aViewMenu = new viewMenu( $active_link );
$aViewMenu->view();

However, I'm nearly new to MVC in PHP, and I welcome reproach.