my $sub = sub { my ($str) = @_; sub { $str } }->($str);

##</code><code>##

my $sub = sub { my $str = $str; sub { $str } }->();

##</code><code>##

my $sub = do { my $str = $str; sub { $str } };

##</code><code>##

my $str_copy = $str;
my $sub = sub { $str_copy };

##</code><code>##

for my $str (...) {
   ... sub { ... $str ... } ...
}

##</code><code>##

sub make_list_iterator { 
   my @list = @_;
   return sub {
      return @list ? shift(@list) : ();
   };
}

my $iter = make_list_iterator(@list);