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(PHP 5 >= 5.3.0)
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.
$storage
)$object
[, mixed $data
= NULL
] )$object
)$object
)$object
)$object
)$object
)$object
[, mixed $data
= NULL
] )$object
)$storage
)$storage
)$data
)$serialized
)
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 ));
?>
以上例程会输出:
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 ]);
}
?>
以上例程会输出:
array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(3) }
[#1] kris dot lamote at it-kitchen dot be [2015-05-22 07:41:46]
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 $serialized;
}
}
?>
[#2] m dot drewek at smf dot de [2015-01-28 08:49:22]
Please note that SplObjectStorage has a Bug introduced with 5.4.0, breaking object lookup in cloned instances of derived classes that overwrite getHash().
This is a confirmed Bug: https://bugs.php.net/bug.php?id=67582
Example:
<?php
class MyObjectStorage extends SplObjectStorage {
// Overwrite getHash() with just some (working) test-method
public function getHash($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
?>
[#3] Marius [2014-11-20 10:54:02]
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";
}
?>
[#4] Adam Monsen [2014-01-07 17:48:21]
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
[#5] inwebo at gmail dot fr [2012-02-28 23:01:00]
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);
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.
[#6] Jan Walther [2011-06-30 06:57:03]
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());
?>
[#7] randallgirard at hotmail dot com [2009-12-14 12:01:35]
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!!