{
    package MyBase;

    sub is {
        my $self = shift;
        my ($type) = @_;

        my $method = 'is_' . $type;

        if (my $code = $self->can($method)) {
            return $self->$code;
        }

        return 0;
    }
}

{
    package Foo;
    use base MyBase::;
    sub is_foo { 1 }
}
{
    package Bar;
    use base MyBase::;
    sub is_bar { 1 }
}
{
    package FooAndBar; # Faker!
    use base MyBase::;
    sub is_foo { 1 }
    sub is_bar { 1 }
}

printf "%-9s %s %s\n", $_, $_->is('foo'), $_->is('bar')
    for Foo::, Bar::, FooAndBar::;

__END__
Foo       1 0
Bar       0 1
FooAndBar 1 1