Compiler Optimizations

I brought this up on another thread, but it wasn't addressed (which is fine, since it was somewhat off-topic). I thought it might be worth bringing up in its own thread, though. In the other thread, someone had mentioned the following compiler optimization foreach(\array_keys($arr) as $key) { and quietly transform that into: foreach ($arr as $key => $_unusedVariableNameThatIsntEvenSpilledToTheScope) { I would be more likely to write: $keys = array_keys($arr); foreach($keys as $key){ Which would prevent me from being able to take advantage of the optimization. So, what I was wondering, is if there are other optimizations I might be missing out on, and if so, are they documented anywhere? -- Chase Peeler chasepeeler@gmail.com