Quote Originally Posted by KLB
Okay, sure if I were writing brand new code, I might consider focusing it on PHP5. Only if, however, my current web host supported PHP5. I'm not going to change web hosts simply to get PHP5.

Why, however, should I have to go through tens of thousands of lines of code to get my PHP4 scripts to work on PHP5? There is no business sense to this. Rewriting code for PHP5 will not improve my profit margin nor will it decrease my costs. It only represents a major cost with no appreciable benefit.

For the most part, I love open source software. My website is hosted on a FreeBSD/Apache/PHP/MySQL server and I use Firefox. With that said, not making sure that PHP5 was backwards compatible with PHP4 or at least making sure it could run parallel to PHP4 was at the very least very stupid. Expecting everyone to jump to upgrade simply because it is an upgrade and the PHP developers say to jump is arrogant.

I certainly hope that the PHP developers learn from their mistakes with PHP5 and make sure that PHP6 plays nice with legacy code or at least plays nice with parallel installs of PHP4/PHP5. If they don't do this, it will fragment PHP support resulting in a balkanization of PHP.
Honestly, you shouldn't have to spend much time on converting at all. I agree that from a business point of view it does not seem very profitable at first. However, doing a few changes here and there (with 10,000 lines of code you shouldn't have to spend more than two days on it, I think probably even less) might make future development even easier.