#!/usr/bin/perl
use strict;
use warnings;
use diagnostics;

my $alpha = qq(alpha="first");
my $beta  = qq(beta="second");
my $gamma = qq(gamma="third");

my $s1 = qq($alpha $beta $gamma);
my $s2 = qq($alpha $gamma $beta);
my $s3 = qq($beta $alpha $gamma);

#my $pat = qr/\b(beta="second")/;
my $pat = qr/(?:\A|\s)(beta="second")(?:\s|\Z)/;

print "s1: \'$s1\', match=".($s1 =~ $pat ? $1 : "nada")."\n";
print "s2: \'$s2\', match=".($s2 =~ $pat ? $1 : "nada")."\n";
print "s3: \'$s3\', match=".($s3 =~ $pat ? $1 : "nada")."\n";

##</code><code>##

s1: 'alpha="first" beta="second" gamma="third"', match=beta="second"
s2: 'alpha="first" gamma="third" beta="second"', match=beta="second"
s3: 'beta="second" alpha="first" gamma="third"', match=beta="second"