--Instance Variables: The new value of each
instance variable of the receiver objects of A and B under the execution order A;B must be the same as the new value under the execution order B;A.
Each object implements its state using a set of
instance variables. Each
instance variable can be either a nested object, a primitive type from the underlying language such as an integer, a double or a pointer to an object, or an array of nested objects or primitive types.
For each
instance variable <name>, the accessor generator looks for <name> and raw<name>.
GS: Rather than having class definitions that just list their
instance variables, our class definitions largely consist of attribute definitions.
To take one example, object-oriented programming languages differ on whether the
instance variables of a superclass are visible to the methods of a subclass.
A subclass inherits the properties (
instance variables and methods) of its parent class(es).
Objects used in object-oriented programming systems are organized into hierarchical classes, and each class of objects has information about its attributes stored in
instance variables associated with each instance of the class.