devel/p5-Class-Std 0.013

Most programmers who use Perl's object-oriented features construct their objects by blessing a hash. But, in doing so, they undermine the robustness of the OO approach. Hash-based objects are unencapsulated: their entries are open for the world to access and modify.

Objects without effective encapsulation are vulnerable. Instead of politely respecting their public interface, some clever client coder inevitably will realize that it's marginally faster to interact directly with the underlying implementation, pulling out attribute values directly from the hash of an object.