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Re: how to measure strictness of a regex ?

by tobyink (Abbot)
on Jan 23, 2013 at 00:30 UTC ( #1014819=note: print w/replies, xml ) Need Help??


in reply to how to measure strictness of a regex ?

re::regmust may be of some help...

use 5.014; use strict; use warnings; use re (); use List::Util 'sum'; sub re_strictness ($) { sum map length, re::regmust shift } say re_strictness qr/Dad+y/; # says 5 say re_strictness qr/D.+/; # says 1
package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

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Re^2: how to measure strictness of a regex ?
by AnomalousMonk (Canon) on Jan 23, 2013 at 01:22 UTC

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

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

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[Lady_Aleena]: Why does grep(/.*$in.*/, @my_modules) work but grep { $_ =~ /.*$in.*/; $_ } @my_modules not work? What did I do wrong in the second?
[tobyink]: Why are you returning $_ n your grep block? You should return a boolean.
[tobyink]: *in your grep block
[tobyink]: You can use grep { $_ =~ /.*$in.*/; } @my_modules but why not stick to grep(/.*$in.*/, @my_modules)? (The latter is faster.)
[shmem]: Lady_Aleena, in the first example grep evaluates the result from grep and if true, returns $_. In the second, it always returns $_
[shmem]: ..the result from the pattern match

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