On Sun, 01 Jul 2012 14:23:36 +1000, Chris Angelico wrote: > On Sun, Jul 1, 2012 at 2:17 PM, Steven D'Aprano > <steve+comp.lang.pyt...@pearwood.info> wrote: >> Nonsense. Of course parens change the evaluation of the expression. >> That's what parens are for! > > The whole point of my example was that it wouldn't.
Yes, you can find specially crafted examples where adding parentheses in certain places, but not others, doesn't change the overall evaluation of the expression. So what? IN GENERAL, adding parentheses changes the evaluation of the expression -- that is what they are for. Therefore, IN GENERAL you should expect that adding parentheses will change the result, unless you carefully place them where you know that they will have no effect. Even in C, I can't just do this: 2+3*4 => (2+3)*4 with the expectation that you can stick parentheses around the left-most term without changing the value. The fact that you can do for some expressions is irrelevant. In general, if you don't know the semantics of an expression (including the operator precedence), you cannot just assume that adding parens is harmless. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
