I'm not the best PHP coder in the world but it seems to me that the development rules should create some limitation on either the length of the line or the number of functions you can call on a single line of code.
The reason? Its confusing and you have to have noticed by now that most of the arbitrary code execution holes you are opening up are from these overly complex overly long lines of code. Be clear, not clever.
Doesn't the Zend engine optimize most of that stuff away anyway? I mean, in my own benchmarking, I didn't see any gain from chainging together a ton of functions.