PHP Clone Object

PHP Clone Object

Summary: in this tutorial, you will learn how to copy objects using shallow copying, as well as using deep copying via PHP clone object.

Let’s start creating a simple Person class for the sake of demonstration.

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php class Person{ private $ssn; private $firstName; private $lastName;   public function __construct($ssn,$firstName,$lastName){ $this->ssn = $ssn; $this->firstName = $firstName; $this->lastName = $lastName; }   public function __destruct(){ echo sprintf("Person with SSN# %s is terminated. ", $this->ssn); }   public function __toString(){ return sprintf("SSN: %s, Name: %s, %s ", $this->ssn, $this->lastName, $this->firstName); } }

Now, we can create some Person objects:

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$p1 = new Person('1234567888', 'Doe', 'John'); echo $p1;   $p2 = new Person('1234567889','Grace','Dell'); echo $p2;

We’ve created two objects:  $p1 and $p2. Both  $p1 and  $p2 are references pointing to the different person objects.

We’ve created two objects:  $p1 and $p2. Both  $p1 and  $p2 are references pointing to the different person objects.

What will happen if we do the following:

1	$p2 = $p1;

Both  $p1 and  $p2 are now pointing to the same object. However the destructor of the $p2 is called because the object that  $p2 is pointing is no longer in used or out of scope.

As we have seen, no real object was created when we assigned $p1 to $p2, only the reference was changed. The way that we’ve copied object is known as shallow copy.

To perform a deep copy that results in creating a new object, we use clone operator as follows:

1	$p2 = clone $p1;

When we execute the statement, the  $p2 reference is pointing to the newly created object. In addition, during the execution, the __clone() magic methods is invoked automatically.

We can add the __clone() magic methods to the Person class to see how it works.

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public function __clone(){ echo 'Copying object <br>'; }