On Wed, Dec 10, 2014 at 11:10 AM, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > On the other hand, *premature optimization*. In general, one shouldn't write > more complex code so the compiler can optimize it, one should write simpler > code and have a smarter compiler. If *we* are capable of recognising that > iters is not modified in the body of the loop, then the compiler should be > capable of it too. (If it isn't, it is because nobody has bothered to give > the compiler sufficient smarts, not because it can't be done.) So a good > compiler should be able to compile "while iters" into "if iters: while > True" so long as iters is not modified in the body of the loop.
In general, one can't expect the boolification of a Python object to be consistent, so the compiler can't optimize this. How can it be sure the list will never become empty? I'm still of the opinion that a while loop's header implies something about the code; "while iters:" implies that iters might be able to become false. Sure, you can verify easily enough that it never will... but why should you have to verify at all? ChrisA -- https://mail.python.org/mailman/listinfo/python-list
