SplObjectStorage::getHash
(PHP 5 >= 5.4.0)
SplObjectStorage::getHash — Calculate a unique identifier for the contained objects
说明
$object
)This method calculates an identifier for the objects added to an SplObjectStorage object.
The implementation in SplObjectStorage returns the same value as spl_object_hash() .
The storage object will never contain more than one object with the same identifier. As such, it can be used to implement a set (a collection of unique values) where the quality of an object being unique is determined by the value returned by this function being unique.
参数
-
object -
The object whose identifier is to be calculated.
返回值
A string with the calculated identifier.
错误／异常
A RuntimeException is thrown when the returned value is not a string .
范例
Example #1 SplObjectStorage::getHash() example
<?php
class OneSpecimenPerClassStorage extends SplObjectStorage {
public function getHash ( $o ) {
return get_class ( $o );
}
}
class A {}
$s = new OneSpecimenPerClassStorage ;
$o1 = new stdClass ;
$o2 = new stdClass ;
$o3 = new A ;
$s [ $o1 ] = 1 ;
//$o2 is considered equal to $o1 so the value is replaced
$s [ $o2 ] = 2 ;
$s [ $o3 ] = 3 ;
//these are considered equal to the objects before
//so they can be used to access the values stored under them
$p1 = new stdClass ;
$p2 = new A ;
echo $s [ $p1 ], "\n" ;
echo $s [ $p2 ], "\n" ;
?> 以上例程的输出类似于：
2 3
参见
- spl_object_hash() - 返回指定对象的hash id
用户评论:
[#1] aron dot duby at gmail dot com [2012-12-17 07:09:07]
This also appears to be the function which gets used within the contains() function, so if all the objects you are storing already have a unique id you can overwrite this function with your own class.
<?php
class UserStorage extends SPLObjectStorage{
public function getHash($obj){
return $obj->id;
}
}
$us = new UserStorage();
$user1 = new User(1);
$user2 = new User(2);
$us->attach($user1);
$us->attach($user2);
$me = new User(2);
// the following would normally fail since they are two separate objects
// but it works now with our extended getHash()
$us->contains($me);
?>