Safer Polymorphism with UNIVERSAL

Another option is to check if the object has the method before calling it.  All objects inherit implicitly from a class called UNIVERSAL, which provides a handful of methods:

    if ($object->can("foo")) {
      print $object->foo;
    }
    else {
      warn "Your object can't even foo";
    }

In addition to can, it also provides isa, which allows you to check whether an object "is a" certain thing.