Re: grep with looped tests

[LanX]

I couldn't resist solving this with 2 nested grep! =)

  DB<100> @x=1..10
 => (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

  DB<101> @re=qw/ 3 7 1 /
 => (3, 7, 1)

  DB<102> grep { my $data=$_; grep { $data =~ /$_/ } @re } @x 
 => (1, 3, 7, 10)

[RichardK]

Similarly, using first from List::Util to short circuit the inner loop when you match a line :)

use v5.18;
use warnings;

use List::Util 'first';
use Data::Dumper;

my @data = 0..10;
my @re = (3,7,9);

my @res = grep {my $line = $_; !defined first {$line =~ $_} @re } @dat
+a;

say Dumper(\@res);

[LanX]

Ah I always forget that List::Util (which is core) has now any , too!

(I'm still hooked on List::MoreUtils , see next answer :)

> my @res = grep {my $line = $_; !defined first {$line =~ $_} @re } @data;

But I think you'd certainly prefer any over first to avoid !defined ! :)

update

though first was and any wasn't part of my 5.10 distribution!

[Laurent_R]

This is a quite nice construct. I had a somewhat similar problem to solve a couple of weeks ago and did not think about such a clever and concise solution. Having said that, the explicit loop I used was probably not less efficient. But I wish I had thought about such a solution as yours.

Rolf, if I may, a brief side question: which option of the debugger are you using for displaying directly last evaluated expression without having to print is explicitly? I mean, when you have this:

  DB<100> @x=1..10
 => (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

what option do you use to have the second line above printed seemingly automatically? Thanks for your response, and sorry for being off-topic.

[LanX]

Unfortunately there is no option, I patched the code. (after a hint here from pemungkah )

Actually monkey patched some lines from a config file.

I can share later if you want, I'm mobile ATM.

[Laurent_R]

Thanks for your answer, Rolf. I am not sure I want to patch Perl, I don't want to break everything, unless it is a simple thing that can be easily undone.