join q{|}, XXX \@{YYY}

##</code><code>##

my $quotemeta = 'XXX';
my $var_name = 'YYY';
my $perl5patt = qq{(??{join q{|}, $quotemeta \@{$var_name}})};
print $perl5patt, "\n";

##</code><code>##

(??{join q{|}, XXX @{YYY}})