Please enable JavaScript.

Coggle requires JavaScript to display documents.

Object-Oriented Paradigm - Coggle Diagram

- - - - Composition represents the whole/part relationship between classes
      - The parts of a class have the same
        lifespan as their owner
      - The parts cannot be involved in another composition
    - - A similar but more relaxed compositional relationship is called aggregation
      - In UML, aggregation is represented using a hollow diamond arrowhead
      - Parts involved in an aggregation relationship do not have to share the same lifespan as the owner
    - - Association represents the logical relationship among classes
      - Composition is one specific type of association
      - In UML, an association is represented by a solid line and it has the following parts: name of the association, end type at each end of the association link, and multiplicity at each end
    - - In an OO design, very often two or more classes may have a large set of attributes and operations in common
      - In UML, the inheritance relationship is represented using a line with a closed arrowhead
      - If the line is dashed, it is a realization relationship.
    - - The OO paradigm provides two different approaches for reusing a design: composition (aggregation) and inheritance
      - Here are three general principles to follow to make the right decision:
        
        Use the inheritance relationship only when the derived class "is-a" base class.
        
        Composition (or aggregation) can be used to model the "has-a" relationship among classes
        
        Be careful when using inheritance. Inheritance could possibly
        weaken the encapsulation of an OO design
- - - - Use the inheritance relationship only when the derived class "is-a" base class.
      - Composition (or aggregation) can be used to model the "has-a" relationship among classes
      - Be careful when using inheritance. Inheritance could possibly
        weaken the encapsulation of an OO design
- - - - Then a class diagram is constructed to further clarify
        the relations among the classes
      - Based on the analysis of use cases, interaction
        diagrams also are drawn to depict the flow of events
    - - Then state machine diagrams are developed to
        describe further design details.
  - - - Domain users are the experts in the business
        model
      - Each OO design analyst is assigned one or more cards and plays the role of the cards.
  - - - In a sequence diagram, the boxes on the top of the diagram denoteobjects, classes, or actors
      - To the left of the colon (:) is the optional object name; to the right is the class name
      - If the object name is anonymous, the left part is left empty.
  - - - A constructor operation is used to initialize the data members of an object when it is created
      - A destructor operation is used to clean up memory and free system resources when an object is no longer in use
      - An accessor operation retrieves information from the object—it can retrieve the value of a data member, or finish some computation based on the state of the object
      - A mutator operation resets the value of one or more object attributes
  - - - A system with a set of highly interdependent classes is very hard to maintain because a change in one class may result in cascading updates of other classes.
      - In an OO design, tight coupling may be removed by introducing
        new classes or inheritance
    - - Coupling and cohesion are two well-known design concepts
      - While coupling involves two or more classes, cohesion is about the design of a single class
      - A cohesive class is one that performs a set of closely related operations.
      - If a class performs unrelated operations, it is said to lack cohesion
    - - The principle encourages OO designers to practice the following two guidelines:
        
        1. Open to extension: the system should have the ability to be extended to meet new requirements.
        
        2. Closed to modification: the existing implementation and code of the system should not be modified as a result of system expansion.