sub map_pairs(&@) {
  my $fn = shift;

  my $pkg = $main::{caller().'::'};

  map {
    @{$pkg}{qw(a b)} = \(@_[0,1]);
    $fn->(shift, shift);
  } (0..$#_/2);
}

package Smarter;
our($a, $b) = qw(orig value);
my @arr = qw(a b c d);
print main::map_pairs {$_[0] = uc($a); print "[$a $_[1]]\n"; $a} @arr;
print "\n";
print "Now @arr\n";
print "\n$a $b\n";