On 2014年3月10日 14:26:14 +1100, Chris Angelico <[email protected]> wrote: > On Mon, Mar 10, 2014 at 1:16 PM, Jim J. Jewett <[email protected]> wrote: > > I don't claim that syntax is perfect. I do think it is less flawed > > than the no-parentheses (or external parentheses) versions: > > > > (expr1 except expr3 if expr2) > > expr1 except expr3 if expr2 > > > > because the tigher parentheses correctly indicate that expr2 and expr3 > > should be considered as a (what-to-do-in-case-of-error) group, which > > interacts (as a single unit) with the main expression. > > But it doesn't, really. The entire set of three expressions is a > single unit. You can't break out the bit inside the parens and give > that a name, like you can in most places where something "acts as a > single unit" to interact with something else. (Yes, there are special > cases, like the syntax for constructing slice objects that works only > inside square brackets. And you can't break out a function's > arguments, as a unit, into a single object (the nearest is > *args,**kw). I said most places, and I don't want to add more to the > special-case set.)
Actually, function arguments almost aren't a special case any more: >>> import inspect >>> def a(a, b=2): ... print(a, b) ... >>> def b(c, d=3): ... print(c, d) ... >>> sa = inspect.signature(a) >>> print(sa) (a, b=2) >>> ba = sa.bind(1, 2) >>> b(*ba.args, **ba.kwargs) 1 2 Note: I said *almost* :) But the point is that we found that the fact that we couldn't give this thing in parens a name bothersome enough to partially fix it. --David _______________________________________________ Python-Dev mailing list [email protected] https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com