That's really a bad idea in the general case, because it won't work if $k has a string terminator in it:

sub emphasizePrint
{
  my $k = qq{"!!\n};
  return sub {
    my ($str) = @_;
    eval (qq{print "$str$k"});
    print STDERR "Error: $@" if ($@);
  }
}
__END__
Error: Can't find string terminator '"' anywhere before EOF at (eval 1
+) line 2.
[download]

In the general case this opens lots of holes, which can be a security risk.

I think that citromatik deliberately interpolated the variables at eval time, not prior to evaling the string.