Magic methods in PHP – Part 1

When we are developing web systems using PHP, we might encounter to use magic methods in PHP a lot. Today I would like to talk about some important magic methods provided by PHP.

Actually there are lots of magic methods in PHP. For example,

• __construct()
• __destruct()
• __call($fun, $arg)
• __callStatic($fun, $arg)
• __get($property)
• __set($property, $value)
• __isset($content)
• __unset($content)
• __sleep()
• __wakeup()
• __toString()
• etc..

But we don’t use all of the things unless it’s necessary. I will only write about a few methods which are mostly used in my experience.

Construct

If you define this method in your class, it will be called automatically when an object is instantiated. The purpose of this method is to assign some default values to the properties of the object. This method is also called a constructor.

<?php
class Student {
    private $name;
 
    public function __construct($name) 
    {
        $this->name = $name;
    }
}
 
$student = new Student('yuuma');
?>

Destruct

The __destruct () method is called destructor and is called when the object is destroyed. Generally also called when script stops or exits. The purpose of this method is to provide an opportunity to save the state of the object or any other cleaning you want to do.

<?php
class Student {
    private $name;
 
    public function __construct($name) 
    {
        $this->name = $name;
    }
 
    public function __destruct() 
    {
        echo 'This will be called when the class has been closed';
        // file close, removing session etc.
    }
}
 
$student = new Student('yuuma');
?>

Set

The magic __set () method is called when you try to set data on properties of inaccessible or non-existent objects. The purpose of this method is to set additional object data for which you have not explicitly defined object properties.

<?php
class Student {
    protected $data = array();
 
    public function __set($name, $value) 
    {
        $this->data[$name] = $value;
    }
}
 
$student = new Student();
//  __set() called
$student->name = 'yuuma';

As you can see from the example above, we are trying to set the property of the name, which does not exist. And so the __set () method is called. The first argument to the __set () method is the name of the property that is being accessed, and the second argument is the value we are trying to set.

Get

In the case of the __set () method example in the previous section, we discussed how to set values for non-existent properties. The __get () method is the exact opposite. The magic __get () method is called when you try to read data from properties of inaccessible or non-existent objects. The purpose of this method is to provide values for these properties.

<?php
class Student {
    private $data = array();
 
    public function __set($name, $value) 
    {
        $this->data[$name] = $value;
    }
 
    public function __get($name) 
    {
        If (isset($this->data[$name])) {
            return $this->data[$name];
        }
    }
}
 
$student = new Student();
 
//  __set() called
$student->name = 'yuuma';   
 
//  __get() called
echo $student->name;                      
?>

I would like to write more but I think the article is a little bit long for now. So I will write a part 2 in next week relating with this week article. So see you next week.

By Yuuma