I managed to save a byte while golfing (unrelated, and sorry about stupid links), then wondered why did it work at all. With following SSCCE, the least level of consistency I'd expect is same output for both "for" cases, but hesitate to point which result of the two is correct and must be the same for them all, perhaps "1 2 2 2 1"?

use strict;
use warnings;

print "map\t";
1 =~ /1/; 
map {
    print "$& ";
    2 =~ /2/; 
    print "$& ";
} 0, 1;
print "$&\n";

print "block\t";
my $n = 1;
1 =~ /1/; 
{
    print "$& ";
    2 =~ /2/; 
    print "$& ";
    redo if $n --
};
print "$&\n";

print "foreach\t";
1 =~ /1/; 
for (0, 1) {
    print "$& ";
    2 =~ /2/; 
    print "$& ";
}
print "$&\n";

print "while\t";
my $m = 2;
1 =~ /1/; 
while ($m --) {
    print "$& ";
    2 =~ /2/; 
    print "$& ";
};
print "$&\n";

print "for\t";
1 =~ /1/; 
for (my $i = 0; $i <= 1; $i++) {
    print "$& ";
    2 =~ /2/; 
    print "$& ";
}
print "$&\n";

__END__

map     1 2 1 2 1
block   1 2 1 2 1
foreach 1 2 2 2 1
while   1 2 2 2 1
for     1 2 1 2 1

[download]

In reply to Regexp vars localization in blocks by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.