use strict;
use warnings;

my $w = q{};
my $x = q{};
my $y = q{};
my $z = q{};

cmpOr();

$x = q{abc};
cmpOr();

$z = q{abcdefghij};
cmpOr();

$z = q{abcdefgh};
cmpOr();

$y = q{abcdefgh};
cmpOr();

$z = q{abcdefghij};
cmpOr();

sub cmpOr
{
    print
       qq{Comparing OR methods with:-\n},
       qq{     \$w is ->$w<-\n},
       qq{     \$x is ->$x<-\n},
       qq{     \$y is ->$y<-\n},
       qq{     \$z is ->$z<-\n};

    if ($w =~ /abcdefgh/ ||
        $x =~ /abcdefgh/ ||
        $y =~ /abcdefgh/ ||
        $z =~ /abcdefgh/)
    {
        print qq{  orig: true\n};
    }
    else
    {
        print qq{  orig: false\n};
    }

    if (q{abcdefgh} =~ /^(?:$w|$x|$y|$z)$/)
    {
        print qq{johngg: true\n};
    }
    else
    {
        print qq{johngg: false\n};
    }

    print qq{\n};
}
[download]

When run this produces

In the particular circumstance of wanting each variable to match the string exactly, this method could save a deal of typing but it's no use in the general case as you pointed out.

Just out of curiosity I had a try at an alternative to if ( $var_a =~ /^abcde$/ && $var_b =~ /^abcde$/ && .... This is what I came up with.

if (q{abcde} =~ /^(?=$var_a$)(?=$var_b$)(?=$var_c$)/)
[download]

Cheers,

JohnGG

Yes,
if ( $var_a =~ /^abcde$/ && $var_b =~ /^abcde$/ && ....
is not equivalent to
if (q{abcde} =~ /^(?=$var_a$)(?=$var_b$)(?=$var_c$)/)
but it is equivalent to
if (q{abcde} =~ /^(?=\Q$var_a\E$)(?=\Q$var_b\E$)(?=\Q$var_c\E$)/)
Of course, that only works because abcde meets the following conditions:

• abcde doesn't contain any characters with special meanings to regexps.
• You're matching the entire string.

In other words, your "optimization", aside from being hard to read and probably being slower, has very limited usage.

It would be better to use:

my $match = 1;
foreach ($var_a, $var_b, $var_c) {
   next if /abcdefgh/;
   $match = 0;
   last;
}

if ($match) {
   ...
}
[download]

or

if ((grep /abcdefgh/, $var_a, $var_b, $var_c) == 3) {
   ...
}
[download]

or

use List::MoreUtils qw( all );

if (all { /abcdefgh/ } $var_a, $var_b, $var_c) {
   ...
}
[download]

The grep solution is easier to read than the foreach solution, but it has the disadvantage of always executing the regexp for every item in the list. The foreach and the all solutions execute the regexp as few times as possible

(Pardon the lateness of my reply; I was on vacation.)

I hope you had an enjoyable and restful vacation.

As you probably guessed, it wasn't a serious proposal but just a bit of noodling around for fun, finding out what could be achieved. I think Herkum stated in this thread that if you wanted to match an exact literal then the eq comparator would be quicker than firing up the regex engine. That is how I would probably attack it in the real world.

Cheers,

JohnGG