Detailed explanation of __set_state() method in PHP

__set_state(), this static method will be called when calling var_export() to export a class.

Function:

Since PHP 5.1.0, this static method will be automatically called when var_export() is called to export a class.

Parameters:

The only parameter of this method is an array containing classes arranged in the format of array('property' => value, ...) Attributes.

Let’s first take a look at the code and running results without adding __set_state():

Code above:

<?php
class Person
{
    public $sex;
    public $name;
    public $age;
    public function __construct($name="",  $age=25, $sex=&#39;男&#39;)
    {
        $this->name = $name;
        $this->age  = $age;
        $this->sex  = $sex;
    }
}
$person = new Person(&#39;小明&#39;); // 初始赋值
var_export($person);

See the results:

Person::__set_state(array( 'sex' => '男', 'name' => '小明', 'age' => 25, ))

Obviously, all the attributes in the object are printed out

After adding __set_state():

Continue with the code:

<?php
class Person
{
    public $sex;
    public $name;
    public $age;
    public function __construct($name="",  $age=25, $sex=&#39;男&#39;)
    {
        $this->name = $name;
        $this->age  = $age;
        $this->sex  = $sex;
    }
    public static function __set_state($an_array)
    {
        $a = new Person();
        $a->name = $an_array[&#39;name&#39;];
        return $a;
    }
}
$person = new Person(&#39;小明&#39;); // 初始赋值
$person->name = &#39;小红&#39;;
var_export($person);

Continue reading Result:

Person::__set_state(array( 'sex' => '男', 'name' => '小红', 'age' => 25, ))

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