Dynamically Typed has a new posting today from a guest blogger (Jules Szemere) concerning one of the big questions in the community these days - what's keeping you from PHP5?.

What's keeping you from PHP5? For me this question applies on three fronts. It encompasses work we do on SitePoint's PHP codebase, work we undertake for clients' projects and tinkering I do in my spare time.

Only in the latter - the 2am toiling PHP geeks promise to do during the swearing in ceremony - have I made any semblance of a switch to PHP5. SitePoint.com is firmly entrenched in PHP4, even though PHP5 offers many enhancements I'd like to take advantage of.

I suspect many, indeed most, large scale custom built websites using PHP are still running on PHP4 with no plans (short term at least) toward making the switch.

He goes on to suggest that one of the main reasons that more sites haven't made the switch is out of worry from the use of those "undefined behaviors" that PHP 4 programmers know all too well.

PHP5 has much of what I want; it's the premium beer at the minute, but all told I can't yet make the switch. So what's stopping you? And what large sites out there are using PHP5?