supertipo

Supertipo, in the context of type theory and programming, refers to a type that is a common superordinate for a set of more specific subtypes. A supertype defines a general interface or contract that all its subtypes share, and it represents a superset of values that includes all values of its subtypes.

In a type hierarchy, subtypes inherit from their supertype and can be used wherever the supertype is expected. This practice, known as upcasting, enables polymorphism and code reuse by allowing operations to be written against the more general supertype rather than individual subtypes. The relation can be understood set-theoretically: the set of values of a supertype contains the union of the values of its subtypes.

Common examples include a class hierarchy in object-oriented languages, where Animal might be a supertype of Dog and Cat. An instance of Dog can be treated as an Animal, enabling generic handling of different animals. Supertype concepts also appear with interfaces or abstract base classes, where the concrete implementations fulfill the same contract.

Applications and design considerations include enabling polymorphic interfaces, generic programming, and safer abstraction. Good usage often involves the Liskov Substitution Principle, which ensures that objects of subtypes can stand in for the supertype without altering correctness. In data modeling, supertypes help support inheritance and shared attributes across related types, while still allowing specialized subtypes to define additional behavior or data.

Etymologically, the term derives from the idea of a type that sits above other related types, providing a common, more general category.