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

Comparing OR methods with:-
     $w is -><-
     $x is -><-
     $y is -><-
     $z is -><-
  orig: false
johngg: false

Comparing OR methods with:-
     $w is -><-
     $x is ->abc<-
     $y is -><-
     $z is -><-
  orig: false
johngg: false

Comparing OR methods with:-
     $w is -><-
     $x is ->abc<-
     $y is -><-
     $z is ->abcdefghij<-
  orig: true
johngg: false

Comparing OR methods with:-
     $w is -><-
     $x is ->abc<-
     $y is -><-
     $z is ->abcdefgh<-
  orig: true
johngg: true

Comparing OR methods with:-
     $w is -><-
     $x is ->abc<-
     $y is ->abcdefgh<-
     $z is ->abcdefgh<-
  orig: true
johngg: true

Comparing OR methods with:-
     $w is -><-
     $x is ->abc<-
     $y is ->abcdefgh<-
     $z is ->abcdefghij<-
  orig: true
johngg: true
[download]

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