I know that PHP4 is "dead", however there are about two dozen or so of our clients that still are located on servers where PHP4 is used, and we won't get any server upgrades until around a year or two.

I'm just about to start working on refactoring and improving our core web framework, which is now coded for the lowest common denominator, PHP4 ( eg all classes have var $foo ).

I've never done any OO in PHP4 but I'm wondering if I should make different classes for the PHP versions, and based on the version of PHP include that version? The downside I realize is that I would have to update two places if an update was made, and there may be no real world advantage to it.

So if anyone could provide tips on how they support legacy PHP versions, I would greatly appreciate it.