Unless there is some specific reason that you need this code to run on both php4 and php5, then inform your boss/admin that the idea of developing on php5, to deploy on php4 is nuts. If they disagree inform them that they are personally nuts( tell them some guy on the internet said so ). It may be possible to develop php5 code in a php5 env, if you are intimately familiar with the differences between php4 and php5, but if you're that familiar with PHP, then you're worth more than a half-ass software creation enviornment. Basicly it's a catch22 if you're good enough to be able to cope with this enviornment, you shouldn't have to.
