package main;

my $foo = bless sub { $_[0] =~ /foo/ }, FunkOpera;
my $bar = sub {"bar"};

my %funk;
@funk{qw/foonbar foorbar barnfoo barrfoo/} =
   ($foo & $bar, $foo | $bar, $bar & $foo, $bar | $foo);

for (keys %funk) {
    print qq($_("food") returns ), $funk{$_}->('food'}, $/;
    print qq($_("ford") returns ), $funk{$_}->('ford'}, $/;
}

__END__

foorbar("food") returns 1
foorbar("ford") returns bar
barnfoo("food") returns 1
barnfoo("ford") returns 
foonbar("food") returns bar
foonbar("ford") returns 
barrfoo("food") returns bar
barrfoo("ford") returns bar