Inheritance/Single: Difference between revisions

The [[classes | class]] of the new type is a '''subclass''' of the classes rooted in the parent types. When all (in certain sense) properties of the parents are preserved by the derived type, it is said to be a [http[wp://en.wikipedia.org/wiki/Liskov_substitution_principle |Liskov subtype]]. When properties are preserved then the derived type is ''substitutable'' for its parents in all contexts. Usually full substitutability is achievable only in some contexts.

Inheritance can be considered as a relation parent-child. Parent types are sometimes called '''supertype''', the derived ones are '''subtype'''. This relation is [http[wp://en.wikipedia.org/wiki/Transitive_relation |transitive]] and [http[wp://en.wikipedia.org/wiki/Reflexive_relation |reflexive]]. Types bound by the relation form a [http[wp://en.wikipedia.org/wiki/Directed_acyclic_graph directed acyclic graph]] (ignoring reflexivity). With single inheritance it becomes a [http[wp://en.wikipedia.org/wiki/Tree_(graph_theory) |tree]].