[php classes and objects] object copy
The content of this article is about [php classes and objects] object replication, which has a certain reference value. Now I share it with everyone. Friends in need can refer to it
Object replication
Usage scenarios:
1. If you have a GTK window object, the object holds window-related resources. You may want to copy a new window, keeping all the same properties as the original window, but it must be a new object (because if it is not a new object, changes in one window will affect the other window).
2. If object A stores a reference to object B, when you copy object A, and you want the object used in it to be no longer object B but a copy of B, then you must get object A a copy of .
Implementation: Through the clone keyword (this will call the object's __clone() method if possible), the __clone() method in the object cannot be called directly.
$copy_of_object = clone $object;
When an object is copied, PHP 5 will perform a shallow copy of all properties of the object. All reference properties will still be references to the original variables.
void __clone ( void )
When copying is completed, if the __clone() method is defined, the __clone() method in the newly created object (the object generated by copying) will be called and can be used to modify the value of the attribute ( if necessary).
Example #1 复制一个对象<?phpclass SubObject{
static $instances = 0; public $instance; public function __construct() {
$this->instance = ++self::$instances;
} public function __clone() {
$this->instance = ++self::$instances;
}
}class MyCloneable{
public $object1; public $object2; function __clone()
{
// 强制复制一份this->object， 否则仍然指向同一个对象
$this->object1 = clone $this->object1;
}
}$obj = new MyCloneable();$obj->object1 = new SubObject();$obj->object2 = new SubObject();$obj2 = clone $obj;print("Original Object:\n");
print_r($obj);/*
Original Object:
MyCloneable Object
(
[object1] => SubObject Object
(
[instance] => 1
)
[object2] => SubObject Object
(
[instance] => 2
)
)
*/print("Cloned Object:\n");
print_r($obj2);/*
Cloned Object:
MyCloneable Object
(
[object1] => SubObject Object
(
[instance] => 3
)
[object2] => SubObject Object
(
[instance] => 2
)
)
*/?>Related recommendations:
[php classes and objects] magic method
[php classes and objects] traversal
[php classes and objects] overloading
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