Oh, and if you want something really closurey, Sort::MultipleFields. There's no clean way of doing what that does without using closures.

The other obvious approach to that problem is to build some code using eval. In fact, I find that you can almost always replace eval with a closure.

Technically none of the examples from Sort::MultipleFields employ closures; they just use anonymous functions. Closures "close over" a variable.

package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

Here's a closure from it ...

$sortsub = sub($$) {
  $spec->($_[0]->{$field}, $_[1]->{$field}) ||
  $oldsortsub->($_[0], $_[1])
}
[download]

Lemme guess - did you just grep the code for /sub {/? :-)