Question

What is an elegant way to remove an object from an array of objects in PHP?

class Data{

  private $arrObservers;

  public add(Observer $o) {  
    array_push($this->arrObservers, $o);  
  }    
  public remove(Observer $o) {  
    // I NEED THIS CODE to remove $o from $this->arrObservers
  }  
  
}

Answer 1

You can do

function unsetValue(array $array, $value, $strict = TRUE)
{
    if(($key = array_search($value, $array, $strict)) !== FALSE) {
        unset($array[$key]);
    }
    return $array;
}

You can also use spl_object_hash to create a hash for the objects and use that as array key.

However, PHP also has a native Data Structure for Object collections with SplObjectStorage:

$a = new StdClass; $a->id = 1;
$b = new StdClass; $b->id = 2;
$c = new StdClass; $c->id = 3;

$storage = new SplObjectStorage;
$storage->attach($a);
$storage->attach($b);
$storage->attach($c);
echo $storage->count(); // 3

// trying to attach same object again
$storage->attach($c);
echo $storage->count(); // still 3

var_dump( $storage->contains($b) ); // TRUE
$storage->detach($b);
var_dump( $storage->contains($b) ); // FALSE

SplObjectStorage is Traversable, so you can foreach over it as well.

On a sidenote, PHP also has native interfaces for Subject and Observer.