Analyzing the Differences when Upgrading from PHP 4 to 5

Since its full release a few years ago, PHP 5 has emerged as the most prominent object oriented web scripting language. Still, a number of web hosts and previous generating scripts continue to utilize build version 4. This guide aims to help developers and hosts understand the key differences between the versions, underlying the importance of upgrading. To understand how PHP has evolved from an early language (the name itself means “Personal Home Page”) to a modern, OOP language, it’s important to understand how the language has been built to scale.

While version 5.4 has evolved into a new PHP 6 branch, the stable version of PHP 5 has become the gold standard for modern web development. While the new features of PHP 6 allow for 64 bit coding, complete object oriented structures and unique class structures, PHP 5.3 remains the state of the art. As future branches of the language continue to evolve, the language is now on a solid foundation that makes the upgrade from version 4 even more important.

Understanding the scale benefits of modern PHP languages

While PHP 5 can run most code from the previous version, the latest version of the language provides a number of new advantages and innovations that can make the entire upgrade process well worthwhile. The object oriented coding has been significantly streamlined, making it much easier to define objects. You can now define multiple variables with a single object, saving you on lines of code as well as simplifying the data presentation.
With PHP version 4 you had to define multiple objects independently to define multiple user instances but with PHP you can make multiple statements by cloning the same object across a variety of instances:

$o1 = new object ();

$o1->setuser('1');

$o1->setpower('A');

$o2 = clone $o1 ();

$o2->setuser('2');

In fact, the entire presentation of a class of objects is streamlined since you can define a constant in the context of a class, rather than having to declare it globally. Similarlly, you can define classes as private or public, making it easier to add layers of security and properly segment your code with variables $public, $protected and $private.

One major concern with early version of PHP code was the amount of coding required in the context of a class. With PHP 5 you can define an abstract class, which allows you to define methods within the context of a class – this makes it easier to scale up the application over time.

Standardizing the PHP Library and Functions

The evolution of PHP 4 brought about a number of standardized features, but still lacked a primary library. Thanks for development from Zend, PHP 5 features an SPL (standard PHP library) that makes it easy to benefit from standardization across the language. With a standard library, developed based upon protocols from the developers at Zend, it’s easier to work with 3rd party code with standard queries, arrays, XML requests, directories and inputs. As PHP moves to a standard modular structure, a common library helps to standardize a growing language.

One new development that emerged as a common source of PHP extensions and modules in conjunction with PHP 5 is PEAR, or the PHP Extension Application Repository. PEAR makes it easier to distribute common PP components for implementing basic codes for application developers. While PEAR formally began in 1999, it became standardized along with PHP 5 and has its own unique development fork in conjunction with PHP 5. As PHP increasingly competes with Ruby on Rails and frameworks that are emerging from ASP and other languages, the implementation of PEAR and modern classes makes it easier to optimize your PHP web applications to scale.

External Links

• http://www.phparch.com/2010/06/09/the-state-of-php-5-3-support/
• http://lukasz.szmit.eu/2010/02/upgrading-php-on-red-hat-5.html