Python scoping

[Alex Martelli]

"Steve Horne" <sh at ttsoftware.co.uk> wrote in message
news:gqeivsspqj64idsf6rr6dgbekif5t9osfo at 4ax.com...
> On Fri, 27 Oct 2000 00:28:15 +0200, "Alex Martelli"
> <aleaxit at yahoo.com> wrote:
>
> >I recall that in PL/I you may, if you wish, recall the label in
> >the END clause (or was it Ada...?  darn -- big languages, long
> >ago...):
>
> Ada certainly allows some types of blocks to be named, and allows you
> to use those names (for instance) to exit out of multiple layers of
> loop in one go (sound like a hidden goto?)

No, just a very useful and clear multi-level break.  Java has it
too, as, I think I recall, does Perl (Perl's keyword for it being
'last' rather than 'break').  In other languages, you have to fake
this useful control structure with exceptions and try-blocks, or
by wrapping the nested loops in a function that has no other reason
to exist (return acts as the multi-level break).  I find explicit
constructs for named-loop exit far preferable.


> You must specify the block name for 'end' with procedures and
> functions, but cannot (except comments) for ifs, loops etc.

Thanks for refreshing my fogged memory.  I now suspect PL/I was
like that, too.  Dylan, apparently, is the language that lets
you optionally name, in the END construct, what is it that you
are ending, and I think I had this vague subconscious memory
confused with the other languages that let you name blocks at
the start, but not for the purpose of naming the end as well.


Alex