PHP 7.0.6 Released

    The SplObjectStorage class

    (PHP 5 >= 5.3.0, PHP 7)

    Introduction

    The SplObjectStorage class provides a map from objects to data or, by ignoring data, an object set. This dual purpose can be useful in many cases involving the need to uniquely identify objects.

    Class synopsis

    SplObjectStorage implements Countable , Iterator , Serializable , ArrayAccess {
    /* Methods */
    public void addAll ( SplObjectStorage $storage )
    public void attach ( object $object [, mixed $data = NULL ] )
    public bool contains ( object $object )
    public int count ( void )
    public object current ( void )
    public void detach ( object $object )
    public string getHash ( object $object )
    public mixed getInfo ( void )
    public int key ( void )
    public void next ( void )
    public bool offsetExists ( object $object )
    public mixed offsetGet ( object $object )
    public void offsetSet ( object $object [, mixed $data = NULL ] )
    public void offsetUnset ( object $object )
    public void removeAll ( SplObjectStorage $storage )
    public void removeAllExcept ( SplObjectStorage $storage )
    public void rewind ( void )
    public string serialize ( void )
    public void setInfo ( mixed $data )
    public void unserialize ( string $serialized )
    public bool valid ( void )
    }

    Examples

    Example #1 SplObjectStorage as a set

    <?php
    // As an object set
    $s = new SplObjectStorage();

    $o1 = new StdClass;
    $o2 = new StdClass;
    $o3 = new StdClass;

    $s->attach($o1);
    $s->attach($o2);

    var_dump($s->contains($o1));
    var_dump($s->contains($o2));
    var_dump($s->contains($o3));

    $s->detach($o2);

    var_dump($s->contains($o1));
    var_dump($s->contains($o2));
    var_dump($s->contains($o3));
    ?>

    The above example will output:

    bool(true)
bool(true)
bool(false)
bool(true)
bool(false)
bool(false)

    Example #2 SplObjectStorage as a map

    <?php
    // As a map from objects to data
    $s = new SplObjectStorage();

    $o1 = new StdClass;
    $o2 = new StdClass;
    $o3 = new StdClass;

    $s[$o1] = "data for object 1";
    $s[$o2] = array(1,2,3);

    if (isset(    $s[$o2])) {
            var_dump($s[$o2]);
    }
    ?>

    The above example will output:

    array(3) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
}

    Table of Contents

    User Contributed Notes

    Adam Monsen
    2 years ago
    Note some inconsistent/surprising behavior in SplObjectStorage to preserve backwards compatibility. You can't properly use foreach with key/value syntax.

    <?php
    $spl     = new SplObjectStorage ();
    $keyForA = new StdClass();
    $keyForB = new StdClass();
    $spl[$keyForA] = 'value a';
    $spl[$keyForB] = 'value b';
    foreach (    $spl as $key => $value)
    {
            // $key is NOT an object, $value is!
        // Must use standard array access to get strings.
            echo $spl[$value] . "\n"; // prints "value a", then "value b"
    }
    // it may be clearer to use this form of foreach:
    foreach ($spl as $key)
    {
            // $key is an object.
        // Use standard array access to get values.
            echo $spl[$key] . "\n"; // prints "value a", then "value b"
    }
    ?>

    See https://bugs.php.net/bug.php?id=49967
    m dot drewek at smf dot de
    1 year ago
    Please note that SplObjectStorage has a Bug introduced with 5.4.0, breaking object lookup in cloned instances of derived classes that overwrite getHash().

    This is a confirmed Bug: https://bugs.php.net/bug.php?id=67582

    Example:
    <?php
    class MyObjectStorage extends SplObjectStorage {
            // Overwrite getHash() with just some (working) test-method
            public function getHash($object) { return get_class($object); }
    }

    class     TestObject {}

    $list = new MyObjectStorage(); // No issues if using "new SplObjectStorage()"
    $list->attach(new TestObject());

    foreach(    $list as $x) var_dump($list->offsetExists($x)); // TRUE

    $list2 = clone $list;
    foreach(    $list2 as $x) var_dump($list2->offsetExists($x)); // FALSE
    ?>
    kris dot lamote at it-kitchen dot be
    11 months ago
    For anyone having issues with SplObjectStorages containing corrupt member variables after garbage collection (FatalErrorException after serializing): we used following fix to great effect
    <?php

    class FixedSplObjectStorage extends SplObjectStorage
    {

        public function     serialize()
        {
                $goodPortion = 'N;;m:a:0:{}';
                $startKey = 'N;;m:a:';

                $serialized = parent::serialize();

                $startPos = strpos($serialized, $startKey);

            if (    $startPos !== false) {
                    $serialized = substr_replace($serialized, $goodPortion, $startPos, -1);

            }

            return     $serialized;

        }
    }

    ?>
    inwebo at gmail dot fr
    4 years ago
    I needed to merge SplObjectStorages.
    <?php
    // As an object set
    $SplObjectStorage_1 = new SplObjectStorage();

    $object1 = new StdClass;
    $object1->attr = 'obj 1';
    $object2 = new StdClass;
    $object2->attr = 'obj 2';
    $object3 = new StdClass;
    $object3->attr = 'obj 3';

    $SplObjectStorage_1->attach($object1);
    $SplObjectStorage_1->attach($object2);
    $SplObjectStorage_1->attach($object3);

    // Another one object set
    $SplObjectStorage_2 = new SplObjectStorage();

    $object4 = new StdClass;
    $object4->attr = 'obj 4';
    $object5 = new StdClass;
    $object5->attr = 'obj 5';
    $object6 = new StdClass;
    $object6->attr = 'obj 6';

    $SplObjectStorage_2->attach($object4);
    $SplObjectStorage_2->attach($object5);
    $SplObjectStorage_2->attach($object6);

    /**
    * Merge SplObjectStorage
    *
    * @param how many SplObjectStorage params as you want
    * @return SplObjectStorage
    */
    function mergeSplObjectStorage() {
       
            $buffer   = new SplObjectStorage();

        if(     func_num_args() > 0  ) {
                $args = func_get_args();
            foreach (    $args as $objectStorage) {
                foreach(    $objectStorage as $object) {
                    if(    is_object( $object ) ) {
                            $buffer->attach($object);
                    }
                }
            }
        }
        else{
            return     FALSE;
        }
        return     $buffer;
    }

    $merge = mergeSplObjectStorage($SplObjectStorage_1, $SplObjectStorage_2);

    ?>
    <?php
    echo $merge->count();
    ?>
    Will output :
    6

    <?php
    $merge    ->rewind();
    while(    $merge->valid()) {
            $object = $merge->current();
            var_dump($object);
            $merge->next();
    }
    ?>
    Will ouput :
    object(stdClass)#2 (1) {
      ["attr"]=>
      string(5) "obj 1"
    }
    object(stdClass)#3 (1) {
      ["attr"]=>
      string(5) "obj 2"
    }
    object(stdClass)#4 (1) {
      ["attr"]=>
      string(5) "obj 3"
    }
    object(stdClass)#6 (1) {
      ["attr"]=>
      string(5) "obj 4"
    }
    object(stdClass)#7 (1) {
      ["attr"]=>
      string(5) "obj 5"
    }
    object(stdClass)#8 (1) {
      ["attr"]=>
      string(5) "obj 6"
    }

    My two cents.
    Marius
    1 year ago
    Do not use SplObjectStorage::detach when forach'ing over items in the storage as this skips the second (and only second) element.

    Example:

    <?php

    class A {
        public     $i;
        public function     __construct($i) {
                $this->i = $i;
        }
    }

    $container = new \SplObjectStorage();

    $container->attach(new A(1));
    $container->attach(new A(2));
    $container->attach(new A(3));
    $container->attach(new A(4));
    $container->attach(new A(5));

    foreach (    $container as $item) {
        echo     $item->i . "\n";
            $container->detach($item);
    }
    echo     "== Left in storage ==\n";
    foreach (    $container as $item) {
        echo     $item->i . "\n";
    }
    /* Outputs:
    1
    3
    4
    5
    == Left in storage ==
    2
    */
    ?>
    Jan Walther
    4 years ago
    I rewrote some scripts and changed object storage with arrays to SplObjectStorage. At some point I needed support of array_rand() but I did not find a function to return a random attached object of an SplObjectStorage object.

    So here is my solution for random access to SplObjectStorage:

    <?php
    $o1     = new StdClass;
    $o2 = new StdClass;
    $s = new SplObjectStorage;
    $s->attach($o1);
    $s->attach($o2);

    $random = rand(0,$s->count()-1);
    $s->rewind();
    for(    $i=0;$i<$random;$i++) {
          $s->next();
    }
    var_dump($s->current());
    ?>
    randallgirard at hotmail dot com
    6 years ago
    I have two things to note about SplObjectStorage:

    #1: A reference to the object itself is stored (not just a hash to compare against the object) and it must be removed before the object is destroyed and the destructor is executed.

    #2: SplObjectStorage::rewind() MUST be called to initiate the iterator and before SplObjectStorage::current() will return an object (and I think the only way to retrieve an object?) rather than automatically starting at the first element as I expected it to, like an array for example. This assumption is based on SplObjectStorage::current() returning NULL until SplObjectStorage::rewind() is called once the objects are contained. As a note, always use REWIND before iterating through or fetching objects.

    <?php

    class foo {
        public function     __destruct() {
            print(    "--- DESTRUCTOR FIRED!!<br />\r\n");
        }
    }

    # Create object and storage
    $bar = new foo();
    $s = new SplObjectStorage();

    # Rewind early just as a test
    $s->rewind();

    # attach the object
    $s->attach($bar, array('test'));

    # Unset the object; destructor does NOT fire
    unset($bar);
    print(    "Object has been unset<br />\r\n");

    # First demonstrate that REWIND must be called to initialize the iterator
    $obj = $s->current();
    var_dump($obj);
    print(    "- Note the NULL (from \$s->current())<br />\r\n");

    # Initialize, and then detach the current (and only) object
    $s->rewind();
    $s->detach( $s->current() );

    # The destructor should NOW execute

    ?>

    Output:

    Object has been unset
    NULL - Note the NULL (from $s->current())
    --- DESTRUCTOR FIRED!!
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