Drupal has joined hands with the 'Go PHP 5' movement that is pushing for wider PHP 5 adoption. Robert Douglass writes that as of Drupal 7, changes to Drupal which use language features found exclusively in PHP 5.2 will be considered for acceptance into Drupal core. This policy effectively means that Drupal 7 will be incompatible with PHP 4.

Robert added that the upcoming Drupal 6 and all current Drupal releases will remain PHP 4-compatible for as long as they are supported. In Drupal 6, contributed Drupal modules and themes may declare their PHP version compatibility. Contributed modules can only be installed on systems that support the required PHP version. This change will allow developers to leverage PHP 5 features without breaking existing Drupal sites. This feature will let Drupal users evaluate the advantages of moving their sites to PHP 5.

Although PHP 5 has been deployed and tested in production environments for three years, web hosts have been slow to adopt PHP 5, making it difficult for Drupal and many other PHP projects to fully embrace PHP 5's features. The 'Go PHP 5' consortium of PHP projects have joined together and push for wider PHP 5 adoption. By embracing PHP 5 together, the projects involved in the GoPHP 5 effort are sending a message to web hosts that it is time to embrace PHP's future.

The project aims to achieve compatibility with PHP 5.2 by the 5th February 2008. The consrtium says that PHP 5.0.x had a number of problems with stability and performance. Much of the feature set wasn't fully nailed down yet either, and tools such as SPL and PDO didn't work right until PHP 5.1. Many developers and web hosts shied away from PHP 5 because of it's unfortunately rocky beginnings. Fortunately, PHP 5.0 is not very widely used. PHP 5.1 was much more stable and reliable, but it also had some issues with performance. It's a viable platform, however, and many projects already require it. PHP 5 has really come into its own with PHP 5.2, however. Robert lists the notable benefits and features like this:

* Improved performance and a more accurate memory usage
* Better security through the filter extension
* ZIP extension for creating and editing zip files
* Hooks for tracking file upload progress were introduced (will let us write an accurate progress tracker for file uploads)
* DateTime and DateTimeZone objects with methods to manipulate date/time information
* SQLite has been bundled with PHP
* Vastly improved XML support (critical for many things, including feeds and aggregation)
* Real opportunities for object oriented programming