php object-oriented Clone and serialization

There are three options for copying objects:

1, direct copy $a = $b

This is a shallow copy, when $a is changed, $b will also change, because They point to the same heap area

2, clone copy $a = clone $b

This copy seems to be a deep copy. When $a changes, $b will not follow. At the same time, PHP provides the magic method __Clone() to customize Clone replication. Which attributes do not want to be copied and what changes are needed during the replication process can be customized in the __clone() method.

However, this copying method has a flaw. It should be noted that if the type of a certain attribute in the class is another class, then this attribute will not be deep copied during Clone. , isn’t it embarrassing? Of course, this shortcoming can be made up for by the magic method __clone. Just create a new new class for this attribute in the __clone() method.

	class test{
		private $name;
		private $sex;
		private $demo;
		public function __construct($name,$sex,$demo){
			$this->name = $name;
			$this->sex  = $sex;
			$this->demo = $demo;
		}
		public function __set($key,$value){
			$this->{$key} = $value;
		}
		public function __get($key){
			return $this->{$key};
		}
		public function __clone(){
			$this->name='null';  //这里可以自定义clone
		}
	}

	class demo{
		private $name;
		public function __construct($name='demo01'){
			$this->name = $name;
		}
		
		public function __set($key,$value){
			$this->{$key} = $value;
		}
		
		public function __get($key){
			return $this->{$key};
		}
	}

	$t = new test('aa', 'bb',new demo('d01'));
	$d = clone $t;
	//$d->name='nihao';
	$d->demo->name = 'd02';
	var_dump($t);   //结果 $t->demo->name   d02

Use clone to make up

		public function __clone(){
			$this->name='null';
			$this->demo = new demo('init');
		}

3, serialized copy

$b = unserialize(serialize($t));

This way you can implement attributes without using the clone magic method A deep copy of the reference type was made.

The above introduces PHP object-oriented Clone and serialization, including aspects of content. I hope it will be helpful to friends who are interested in PHP tutorials.