The SplObjectStorage class

(PHP 5 >= 5.3.0)

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)
}

SplObjectStorage::addAll — Adds all objects from another storage
SplObjectStorage::attach — Adds an object in the storage
SplObjectStorage::contains — Checks if the storage contains a specific object
SplObjectStorage::count — Returns the number of objects in the storage
SplObjectStorage::current — Returns the current storage entry
SplObjectStorage::detach — Removes an object from the storage
SplObjectStorage::getHash — Calculate a unique identifier for the contained objects
SplObjectStorage::getInfo — Returns the data associated with the current iterator entry
SplObjectStorage::key — Returns the index at which the iterator currently is
SplObjectStorage::next — Move to the next entry
SplObjectStorage::offsetExists — Checks whether an object exists in the storage
SplObjectStorage::offsetGet — Returns the data associated with an object
SplObjectStorage::offsetSet — Associates data to an object in the storage
SplObjectStorage::offsetUnset — Removes an object from the storage
SplObjectStorage::removeAll — Removes objects contained in another storage from the current storage
SplObjectStorage::removeAllExcept — Removes all objects except for those contained in another storage from the current storage
SplObjectStorage::rewind — Rewind the iterator to the first storage element
SplObjectStorage::serialize — Serializes the storage
SplObjectStorage::setInfo — Sets the data associated with the current iterator entry
SplObjectStorage::unserialize — Unserializes a storage from its string representation
SplObjectStorage::valid — Returns if the current iterator entry is valid

add a note

User Contributed Notes 5 notes

down

inwebo at gmail dot fr ¶

2 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.

down

Adam Monsen ¶

3 months 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

down

Jan Walther ¶

2 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());


?>

down

-2

Robertas at pobox com ¶

4 years ago


PHP 5.2.x and lower doesn't implement ArrayAccess in SplObjectStorage - it is only implemented starting from PHP 5.3

down

-1

randallgirard at hotmail dot com ¶

4 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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The SplObjectStorage class

Introduction

Class synopsis

Examples

Table of Contents

User Contributed Notes 5 notes