PHP Destructor

Summary: in this tutorial, you will learn about the PHP destructor and use it to clean up the resources when the object is deleted.

Introduction to the PHP destructor

Like the constructor, PHP allows you to define a destructor for a class using a special method __destruct() like this:

<?php

class className
{
	public function __destruct()
	{
		//...
	}
}Code language: HTML, XML (xml)

Unlike a constructor, a destructor doesn’t accept any argument. The destructor is automatically invoked before an object is deleted. It happens when the object has no reference or when the script ends.

PHP destructor example

The following simple FileUtil class demonstrates how to use the destructor to close a file handle:

<?php

class File
{
	private $handle;

	private $filename;

	public function __construct($filename, $mode = 'r')
	{
		$this->filename = $filename;
		$this->handle = fopen($filename, $mode);
	}

	public function __destruct()
	{
		// close the filehandle
		if ($this->handle) {
			fclose($this->handle);
		}
	}

	public function read()
	{
		// read the file contents
		return fread($this->handle, filesize($this->filename));
	}
}

$f = new File('./test.txt');
echo $f->read();Code language: HTML, XML (xml)

How it works.

• First, define the File class with the constructor that accepts two arguments: $filename and $mode. By default, the File class opens the file for reading.
• Second, open the file and assign the file handle to the $handle property in the constructor.
• Third, close the file handle in the destructor.
• Fourth, return the file contents from the read() method.

Summary

• Use the __destruct() to define a destructor for a class.
• PHP automatically invokes the destructor when the object is deleted or the script is terminated.