Re^2: how to measure strictness of a regex ?

[AnomalousMonk]

I, also, have some (admittedly, rather idle) curiosity: what is the purpose of the prototype in the  re_strictness() function definition?

[tobyink]

I think my original code when I was testing was something along the lines of:

print re_strictness qr/.../, "\n";

In which case the ($) prototype helps Perl see the "\n" as a parameter for print, not for re_strictness.

By the way, it's worth pointing out that qr/^Dad+y$/ is also considered slightly stricter than qr/Dad+y/.

use 5.014;
use strict;
use warnings;
use re ();
use List::Util 'sum';

sub re_strictness ($) { sum map length, re::regmust shift }

print
    re_strictness qr/^Dad+y$/, "\n",
    re_strictness qr/Dad+y/, "\n",
    re_strictness qr/D.+/, "\n",
;