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Postings from September 2002
Re: Regex query
From:
John Williams
Date:
September 22, 2002 22:01
Subject:
Re: Regex query
Message ID:
Pine.LNX.4.33.0209221509290.13964-100000@sharkey.morinda.com
On Sat, 21 Sep 2002, Jonathan Scott Duff wrote:
>
> Why can't perl be smart enough to figure out what we mean? Something
> along these lines:
>
> (7) # list context
> (3+4) # numeric context (there's a numeric operator in there)
> (3+4,5) # list context (comma trumps the numeric op)
My understanding of context (which admittedly, may be completely
incorrect) is that context is imposed from the outside. So in (3+4), 3
and 4 are in numeric contect because the '+' says so, but we can't tell
what context (...) is in, because there is no context. + has higher
precendence than comma, so the 3+4 becomes 7 before the comma creates a
list: 7,5.
A different workaround just occurred to me for perl6. Maybe instead of
(7) having list context imposed by the parenthesis, imposing list context
on a scalar automatically creates a 1 item list. So:
@a = (7);
is the same as
@a = 7;
And actually, that works in perl5 too.
So maybe we're arguing about nothing?
> (7,) is an abomination. It's one of python's misfeatures that annoys
> me the most.
Strangely enough, it's one of the features of perl that I really like,
although you have to think of it in the context of
(
'a',
'long',
'list',
'of',
'items',
'one',
'per',
'line', # <-- notice the comma!
)
Of course, _requiring_ the comma is bad, but as long as we can use [7] or
rely on list context creating a single item list out of a single item, it
is not required.
~ John Williams