[Python-ideas] for/except/else syntax
bruce at leapyear.org
Wed Oct 7 06:06:59 CEST 2009
Here you go:
do_except = True
for i in SEQ:
do_except = False
if not do_except:
C # suite_if_loop_is_not_broken
B # suite_if_loop_body_is_not_executed
On Tue, Oct 6, 2009 at 8:53 PM, Guido van Rossum <guido at python.org> wrote:
> On Tue, Oct 6, 2009 at 8:46 PM, Bruce Leban <bruce at leapyear.org> wrote:
> > Switching gears a bit, here's what I want:
> > for_stmt ::= "for" target_list "in" expression_list ":" suite_loop_body
> > ["except" ":" suite_if_loop_body_is_not_executed] ["else" ":"
> > suite_if_loop_is_not_broken]
> > The except and else appear in this order to make it clear that except
> > precedence. If the loop body is not executed at all then both conditions
> > true but it obviously is only useful if except takes precedence.
> > Comments?
> I'm sure it's obvious to you what the except clause should do, but it
> isn't to me. :-( Assuming you're not proposing we change the meaning
> of else in the absence of except, and that its meaning together with
> except is a logical extension of this, can you show how we should
> translate a for-loop with an except clause into current Python? Say,
> what would I be writing today to get the exact effect of your proposed
> for i in SEQ:
> --Guido van Rossum (home page: http://www.python.org/~guido/)
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