>perl -wMstrict -MRegexp::Assemble -le
"my $r =
   Regexp::Assemble->new->track(1)->add(qw(foo? bar{2} [Rr]at));
 for my $w (qw(this food is rather barren)) {
   if ($w =~ /$r/) {
     print qq{'$w' matched by /}, $r->source($^R), q{/};
     }
   else {
     print qq{'$w' unmatched};
     }
   }
"
'this' unmatched
'food' matched by /foo?/
'is' unmatched
'rather' matched by /[Rr]at/
'barren' matched by /bar{2}/