PHP Magic Methods

Summary: in this tutorial, you will learn about PHP magic methods that override the default actions when the object performs the actions.

Introduction to PHP magic methods

PHP magic methods are special methods in a class. The magic methods override the default actions when the object performs the actions.

By convention, the names of magic methods start with a double underscore (__). And PHP reserves the methods whose names start with a double underscore (__) for magic methods.

So far, you have learned that the constructor and destructor use the __construct() and __destruct() methods. In fact, the constructor and destructor are also magic methods.

The __construct() method is invoked automatically when an object is created and the __destruct() is called when the object is deleted.

Besides the __contruct() and __destruct() methods, PHP also has the following magic methods:

This tutorial will focus on the __set() and __get() methods.

PHP __set() method

When you attempt to write to a non-existing or inaccessible property, PHP calls the __set() method automatically. The following shows the syntax of the __set() method:

public __set ( string $name , mixed $value ) : voidCode language: PHP (php)

The __set() method accepts the name and value of the property that you write to. The following example illustrates how to use the __set() method:

<?php

class HtmlElement
{
	private $attributes = [];

	private $tag;

	public function __construct($tag)
	{
		$this->tag = $tag;
	}

	public function __set($name, $value)
	{
		$this->attributes[$name] = $value;
	}

	public function html($innerHTML = '')
	{
		$html = "<{$this->tag}";
		foreach ($this->attributes as $key => $value) {
			$html .= ' ' . $key . '="' . $value . '"';
		}
		$html .= '>';
		$html .= $innerHTML;
		$html .= "</$this->tag>";

		return $html;
	}
}Code language: HTML, XML (xml)

How it works.

• First, define the HTMLElement class that has only one property $attributes. It will hold all the attributes of the HTML element e.g., id and class.
• Second, initialize the constructor with a tag name. The tag name can be any string such as div, article, main, and section.
• Third, implement the __set() method that adds any property to the $attribute array.
• Fourth, define the html() method that returns the HTML representation of the element.

The following uses the HTMLElement class and create a new div element:

<?php

require 'HTMLElement.php';

$div = new HtmlElement('div');

$div->id = 'page';
$div->class = 'light';

echo $div->html('Hello');Code language: HTML, XML (xml)

Output:

<div id="page" class="light">Hello</div>Code language: HTML, XML (xml)

The following code attempts to write to the non-existing property:

$div->id = 'page';
$div->class = 'light';Code language: PHP (php)

PHP calls the __set() method implictily and adds these properties to the $attribute property.

PHP __get() method

When you attempt to access a property that doesn’t exist or a property that is in-accessible e.g., private or protected property, PHP automatically calls the __get() method.

The __get() method accepts one argument which is the name of the property that you want to access:

public __get ( string $name ) : mixedCode language: PHP (php)

The following adds the __get() method to the HTMLElement class:

<?php

class HtmlElement
{
	private $attributes = [];

	private $tag;

	public function __construct($tag)
	{
		$this->tag = $tag;
	}

	public function __set($name, $value)
	{
		$this->attributes[$name] = $value;
	}

	public function __get($name)
	{
		if (array_key_exists($name, $this->attributes)) {
			return $this->attributes[$name];
		}
	}

	public function html($innerHTML = '')
	{
		$html = "<{$this->tag}";
		foreach ($this->attributes as $key => $value) {
			$html .= ' ' . $key . '="' . $value . '"';
		}
		$html .= '>';
		$html .= $innerHTML;
		$html .= "</$this->tag>";

		return $html;
	}
}Code language: HTML, XML (xml)

The __get() method checks if the requested property exists in the $attributes before returning the result.

The following creates a new article element, sets the id and class attributes, and then shows the value of these attributes:

<?php

require 'HTMLElement.php';

$article = new HtmlElement('article');

$article->id = 'main';
$article->class = 'light';

// show the attributes
echo $article->class; // light
echo $article->id; // mainCode language: HTML, XML (xml)

Summary

• PHP Magic methods start with double underscores (__).
• PHP calls the __get() method automatically when you access a non-existing or inaccessible property.
• PHP calls the __set() method automatically when you assign a value to a non-existing or inaccessible property.