Re: Best practice or cargo cult?

[davorg]

As I understand it, these options will all effectively be turned on by default in the Perl 6 regex engine. So either Larry has decided that they are, in fact, best practice or Damian has sneaked them into the specs whilst Larry wasn't watching.

[Juerd]

As I understand it, these options will all effectively be turned on by default in the Perl 6 regex engine. So either Larry has decided that they are, in fact, best practice or Damian has sneaked them into the specs whilst Larry wasn't watching.

Firstly, Perl 6 is not Perl 5.

Secondly, Perl 6 gives you \N, a convenient way to write <-[\n]> (that's [^\n]). It's worse than ., but acceptable. Writing [^\n] all the time is a hard exercise for one's fingers, and makes for messy code. That's why I strongly believe you should only use /s when you really want . to include the newline character.

/m won't be turned on by default in Perl 6. Instead, we get different metacharacters for begin/end of line versus string. So again it gives best of BOTH worlds.

As for /x... I have no strong opinion about that. I don't think /\A\d+\z/ is unreadable, but I don't mind /\A \d+ \z/x at all.

[demerphq]

\N could easily be added to blead. Ill check into it.

[diotalevi]

\N{...} is already a recognized pattern in perl5 regexp language. Pick something else and add it to your current perl using the instructions at Extending Regular Expression Syntax. It's a presentation I gave to Minneapolis.pm last year. Or... co-opt \N for your own use. It isn't as if \N is so common that you'd miss it if you stole it away from perl. In my demo I redefined \w and \b to something more appropriate for my own set of common tasks.

[diotalevi]

In fact, here's the implementation. This works in perl5 going back to uh... early? Have your cake today. Not that I tested it. It's simple enough I just penned this and didn't bother running it.

use Regexp::SlashN;

"A
B
C" =~ /(\N+)/;

$1 eq "A
B
C" or die;

Regexp/SlashN.pm

package Regexp::SlashN;
use overload;
sub import { overload::constant qr => \ &convert }

# A simple table of definitions
my %syntax = ( '\\' => '\\',
               N => '[^\n]', );

sub convert {
    my ( $re ) = @_;
    $re =~ s/\\([\\N])/$syntax{$1}/g;
    return $re;
}