On Thu, Feb 27, 2014 at 7:44 PM, Ronald Oussoren <ronaldousso...@mac.com> wrote: > What about (also mentioned in the PEP)? > > value = (expr except Exception try default) > > This seems to read nicely, although “try” is at a completely different > position than it is in the equivalent try statement. > > I like the general idea, but like Brett I don’t like using a colon here at > all.
I see your "although" clause to be quite a strong objection. In the statement form of an if, you have: if cond: true_suite else: false_suite In the expression form, you have: true_expr if cond else false_expr Personally, I think it's a weakness of the if-expression that they're not in the same order (cond, true_expr, false_expr), but they're still introduced with the same keywords. The 'if' keyword is followed by the condition, and the 'else' keyword by the false "stuff". Putting "try" followed by the default is confusing, because any exception raised in the default-expr will bubble up. Stealing any other keyword from the try/except block would make just as little sense: expr except Exception finally default # "finally" implies something that always happens expr except Exception else default # "else" implies *no* exception expr except Exception try default # "try" indicates the initial expr, not the default default except Exception try expr # breaks L->R evaluation order Left to right evaluation order is extremely important to me. I don't know about anyone else, but since I'm the one championing the PEP, you're going to have to show me a *really* strong incentive to reword it to advocate something like the last one :) This is stated in the PEP: http://www.python.org/dev/peps/pep-0463/#alternative-proposals Using try and except leaves the notation "mentally ambiguous" as to which of the two outer expressions is which. It doesn't make perfect sense either way, and I expect a lot of people would be flicking back to the docs constantly to make sure they had it right. It's hard when there's confusion across languages (try writing some code in REXX and Python that uses division and modulo operators - 1234/10 -> 123.4 in Py3 and REXX, but 1234//10 and 1234%10 have opposite meaning); it's unnecessarily hard to have the same confusion in different places in the same language. ChrisA _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
