ObjectOrientation

ObjectOrientation

1. DEFINITION: Organize software as a collection of discrete objects that incorporate both data structure and behavior

   • Contrasts with previous programming behaviour in which data data structure and behaviour are only loosely connected
     • skillnaden mellan OO och vanlig

2. Kännetecknas av 4 karaktäristika

   • Identity: means that data is quantized into discrete, distinguishable entities called objects. Mike’s bicycle, a monitor, is examples of objects.
   • Classification: means that objects with the same data structure (attributes) and behavior (operations) are grouped into a class.
   • Inheritance: is the sharing of attributes and operations (features) among classes based on a hierarchical relationship. A superclass has general information that subclasses refine and elaborate. Each subclass incorporates, or inherits, all the features of its superclass and adds its own unique features
   • Polymorphism: means that the same operation may behave differently for different classes. The move operation, for example, behaves differently for a pawn than for the queen in a chess game

3. 3 Models to describe a system from different viewpoints

   • Class model: describes the static structure of the objects in a system and their relationships.
   • State model: describes the aspects of an object that change over time. The state model specifies and implements control with state diagrams
   • Interaction model: describes how the objects in a system cooperate to achieve broader results
     • Use case, sequence diagram, activity diagram