On Mon, Jul 18, 2005 at 01:41:52AM -0700, avised @ kbcfp. com wrote:
> This test program:
>
> my $foo = 'foo';
> for ($foo) {
> m!(\w+)! or die;
> print "\$1 has been set to: $1\n";
> }
> print "\$1 is now: $1\n";
>
> gives the output:
>
> $1 has been set to: foo
> $1 is now:
>
> Somehow, although $1 was set it has been changed back to undef on
> exiting the 'for' block. I don't see anything in perlre or perlvar
> documenting this.
Feature, not bug.
>From perlre:
The numbered match variables ($1, $2, $3, etc.) and the related punctu-
ation set ($+, $&, $`, $', and $^N) are all dynamically scoped until
the end of the enclosing block or until the next successful match,
whichever comes first. (See "Compound Statements" in perlsyn.)
$1 and friends have an implicit "local" on them so they are localized to
a block. Its been this way for a long time.
$ perl5.4.5 -wle '$_ = "foo"; { /(\w)/; print $1 } print $1'
f
Use of uninitialized value at -e line 1.
--
Michael G Schwern [EMAIL PROTECTED] http://www.pobox.com/~schwern
'All anyone gets in a mirror is themselves,' she said. 'But what you
gets in a good gumbo is everything.'
-- "Witches Abroad" by Terry Prachett
