CSC308 Lecture 13

Software Engineering I
Design Patterns
(202302)

Transcript

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   CSC 308
   Software Engineering 1
   Lecture 13:
   Design Patterns
   Dr. Javier Gonzalez-Sanchez
   javiergs@calpoly.edu
   www.javiergs.com
   Building 14 -227
   Office Hours: By appointment
   

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   Previously …
   

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   Not Everything that Can be … Should be …
   

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   From Assignment 01
   

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   Homework (1 of 2)
   Single Responsibility
   Principle
   

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   Patterns
   Software Design
   

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   § Design patterns are solutions to software design problems you find again
   and again in real-world application development.
   § Patterns are about reusable designs and interactions between objects.
   § The 23 Gang of Four (GoF) patterns are generally considered the
   foundation for all other patterns (Gamma, Helm, Johnson, and Vlissides).
   Definition
   

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   Timeline
   1989 Beck
   OO Thinking
   1993 Gamma et al.
   GoF Patterns
   

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   GoF Patterns
   

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    GoF Patterns
    

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    Observer
    Software Design
    

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    From Assignment 01
    

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    Observer
    

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    class Student {
    public String answerQuestion (String question) {
    String answer;
    // solve the question
    return answer;
    }
    }
    Student
    

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    class Teacher {
    private String question;
    public String getQuestion() {
    return question;
    }
    public void createQuestion () {
    question = // AI to create a question here
    }
    }
    Teacher
    

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    Observer
    

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    public abstract class Observer {
    public abstract void update(Subject s);
    }
    Observer
    

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    import java.util.LinkedList;
    public abstract class Subject {
    private LinkedList observers = new LinkedList();
    public void addObserver(Observer observer) {
    observers.add(observer);
    }
    public void removeObserver(Observer observer) {
    observers.remove(observer);
    }
    public void notifying() {
    for (Observer ob : observers) {
    ob.update(this);
    }
    }
    }
    Observable
    

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    class Student extends Observer {
    public String answerQuestion (String question) {
    String answer;
    // solve the question
    return answer;
    }
    @Override
    public void update(Observable s) {
    String q = ((Teacher)s).getQuestion();
    Sting answer = answerQuestion (q);
    System.out.println (answer);
    }
    }
    Student as Observer
    

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    class Teacher extends Observable {
    private String question;
    public String getQuestion() {
    return question;
    }
    public void createQuestion () {
    question = // AI to create a question here
    notifying();
    }
    }
    Teacher as Observable
    

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    public class Main {
    public static void main(String[]a) {
    Teacher teacher = new Teacher();
    Student s1 = new Student();
    Student s2 = new Student();
    teacher.addObserver(s1);
    teacher.addObserver(s2);
    // Teaching
    teacher.createQuestion();
    // More Teaching
    teacher.createQuestion();
    }
    }
    Main
    

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    Scenario
    Observer
    + update()
    Observable
    + addObserver()
    + notifyObservers()
    + setChanged()
    Teacher
    Student Main
    

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    Questions
    

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    Office Hours
    Tuesday and Thursday 3 - 5 pm
    But an appointment required
    Sent me an email – javiergs@calpoly.edu
    

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    CSC 308
    Software Engineering 1
    Lab 13:
    Assignment 02
    Dr. Javier Gonzalez-Sanchez
    javiergs@calpoly.edu
    www.javiergs.com
    Building 14 -227
    Office Hours: By appointment
    

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    Project – User create dots
    

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    Project – User selects Cluster and clicks Run
    ✅
    

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    Project – User selects Cluster and clicks Run
    ✅
    

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    Project – User selects Line and clicks Run
    ✅
    

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    Project – User selects Line and clicks Run
    ✅
    

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    Project – User selects Line and clicks Run
    ✅
    ✅
    

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    Project – User selects Cluster and clicks Run
    ✅
    ✅
    

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    CSC 308 Software Engineering I
    Javier Gonzalez-Sanchez, Ph.D.
    javiergs@calpoly.edu
    Winter 2023
    Copyright. These slides can only be used as study material for the class CSC308 at Cal Poly.
    They cannot be distributed or used for another purpose.
    

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