sub make_closure {
   my ($str) = @_;
   return sub { $str };
}

my $str = 'hi';
my $sub = make_closure($str);

say $sub->();   # 'hi'
$str = 'hello';
say $sub->();   # 'hi'

##</code><code>##

my $str = 'hi';
my $sub = eval qq{ sub { "\Q$str\E" } } or die $@;

say $sub->();   # 'hi'
$str = 'hello';
say $sub->();   # 'hi'