PHP4 is seven years old now (amazing!), and PHP5 has been out for nearly three years. But while v4 has gotten pretty long in the tooth, the massive entrenchment of web apps targeted at PHP4 has prevented anything like rapid uptake for version 5. As many as 80% of PHP hosts were still running 4.x as of June 2007. Web hosts who undertake an upgrade risk breaking thousands of customer applications – not OK. But something’s got to break the cycle, which is preventing developers from taking full advantage of all the chocolaty, O-O goodness in v5.
GoPHP5.org is assembling a list of major open source PHP apps committed to dropping all support for v4 by February 2008 as a way to goad hosts into undertaking the difficult transition. The Drupal, Symfony, and phpMyAdmin teams have already signed on, while the WordPress hackers are eager, but wary of the fallout.
I’d be wary of the fallout too. I tried to upgrade my server to PHP5 a year or two back. The results were nightmarish, several days work spent trying in vain to get back to PHP4, and in the end I had to abandon my server and get a new one (I’m not an expert sysadmin, and the tangled dependencies between Plesk and other apps played a large part).
My server still runs PHP4, and there’s no way I’m going to try another upgrade.
We upgraded our server at work with no ill effects, but we don’t have nearly the wide range of PHP software running on it that is installed at Birdhouse. And at work, if something breaks, I’m the one who controls it, so I can fix it. But breaking customer sites at Birdhouse would be a whole ‘nuther matter.