> Use it when you have a PHP 5.4+ codebase and just can't upgrade your client's infrastructure.<p>I personally would just avoid those kinds of clients, PHP 5.4 was released on 1 March 2012 and PHP 5.3 is only supported until 14 August 2014[1].<p>[1] <a href="http://en.wikipedia.org/wiki/PHP#Release_history" rel="nofollow">http://en.wikipedia.org/wiki/PHP#Release_history</a>
5.3 is dead. Acknowledge that, upgrade and move on.<p>The very last thing you should be doing is pandering to infrastructure that "cannot be upgraded". That's BS. Even if you have legacy systems, there's nothing stopping you having another instance of PHP or even another server running current software.<p>Infrastructure management is very much a part of modern web development. If you want to deploy stuff, be ready to educate your clients every so often.