class invariant meaning: definition, quotations

class invariant

noun

An invariant used to constrain objects of a class that is preserved by class methods and that constrains the state stored in the object.

Object-oriented programming

Every object of a given class must satisfy the class's invariant. This invariant acts as a constraint, limiting the size of the class's state-space. A subclass both inherits the class invariant(s) of its superclass(es) and adds a further restriction of its own.2000, Meilir Page-Jones, Fundamentals of Object-oriented Design in UML, Addison-Wesley Professional, →ISBN, page 272: