SplObjectStorage::getHash()
(PHP 5 >= 5.4.0, PHP 7)
Calculate a unique identifier for the contained objects
说明
public SplObjectStorage::getHash(object $object) : string
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
- $object
The object whose identifier is to be calculated.
返回值
A string with the calculated identifier.
错误/异常
A RuntimeException is thrown when the returned value is not a string.
范例
SplObjectStorage::getHash() example
<?php class OneSpecimenPerClassStorage extends SplObjectStorage { public function getHash($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
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); ?>