OBJECT ORIENTED DESIGN

1. OBJECT ORIENTED DESIGN CMPS260 ULL Computer Science Department

2. OBJECT DEFINITION • IDENTIFY THE OBJECTS IN AN APPLICATION • SPECIFY THEIR STRUCTURES, VALUES AND OPERATIONS • HOOK THEM TOGETHER TO SOLVE THE PROBLEM (SWE)

3. OBJECTS • OBJECTS ARE THE ENTITIES IN THE PROBLEM STATEMENT (NOUNS) • OBJECTS HAVE STRUCTURES, VALUES AND OPERATIONS • OBJECTS INTERACT WITH OTHER OBJECTS (VISIBILITY) • OBJECTS ARE ABSTRACTIONS

4. ABSTRACTION • THE REMOVAL OF NON-ESSENTIAL DETAILS • PROVIDES AN INTERFACE FOR THE USER • HIDES THE IMPLEMENTATION FROM THE USER • PROVIDES FOR ENFORCEMENT

5. CLASSES • ABSTRACT DATA TYPES • SPECIFICATION (INTERFACE) • IMPLEMENTATION • COMPILED SEPARATELY • INTERACT VIA MESSAGE PASSING

6. DRIVER • PROCEDURAL CONTROL PROGRAM • CREATES OBJECTS • USES OBJECTS • CONTROLS SYSTEM FLOW • THE SMALLER THE BETTER

7. SUMMARY • OBJECTS ARE THE BASIC COMPONENTS • ABSTRACTIONS ARE DEFINED AND ENFORCED • PROCEDURAL ASPECTS ARE INCLUDED IN THE CLASSES AND THE DRIVER

8. SAMPLE OBJECTS • PERSON • STUDENT (DERIVED FROM PERSON) • COURSE • CLASS (INSTANCE OF A COURSE) • SCHEDULE (CONTAINS A STUDENT AND THEIR CLASSES)

9. EXAMPLE ATM MACHINE INTERFACE VERIFY, WITHDRAW … ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ IMPLEMENTATION HIDDEN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ENFORCEMENT CRITICAL

10. ATM OBJECT DIAGRAM IMPLEMENTATION (HIDDEN) (BETTER BE) INTERFACE (PUBLIC) ACCT DATA ??? USERS VERIFYACCT WITHDRAW FUNDS IN & OUT ??? DEPOSIT CHK BAL

11. ~~~~~~~~~~~~~~~~~~~ SPECIFICATION FILE ~~~~~~~~~~~~~~~~~~~// Declare a class to represent the date ADT// This is file DateType.hclass DateType{public: void Initialize(int newMonth, int newDay, int newYear); int YearIs() const; // returns year; int MonthIs() const; // returns month; int DayIs() const; // returns day; enum RelationType {LESS, EQUAL, GREATER}; RelationType ComparedTo(DateType aDate);private: int year; int month; int day;};

12. ~~~~~~~~~~~~~~~~~~~ IMPLEMENTATION FILE ~~~~~~~~~~~~~~~~~~~// Define member functions of class DateType.// This is file DateType.cpp.#include "DateType.h" // gain access to the specificationvoid DateType::Initialize(int newMonth, int newDay, int newYear)// Post: year is set to newYear.// month is set to newMonth.// day is set to newDay.{ year = newYear; month = newMonth; day = newDay;}// Accessor funtions for the private data membersint DateType::MonthIs() const// Accessor function for month.{return month;}int DateType::YearIs() const// Accessor function for year.{return year;}int DateType::DayIs() const// Accessor function for day.{return day;}

13. RelationType DateType::ComparedTo(DateType aDate)// Pre: Self and aDate have been initialized.// Post: Function value = LESS, if self comes before aDate.// = EQUAL, if self is the same as aDate.// = GREATER, if self comes after aDate.{ if (year < aDate.year) return LESS; else if (year > aDate.year) return GREATER; else if (month < aDate.month) return LESS; else if (month > aDate.month) return GREATER; else if (day < aDate.day) return LESS; else if (day > aDate.day) return GREATER; else return EQUAL;}

14. ~~~~~~~~~~~~~~~~~~~ DRIVER ~~~~~~~~~~~~~~~~~~~#include "DateType.h"#include <iostream>using namespace std;int main(){ DateType today; DateType anotherDay; today.Initialize(8, 24, 2006); anotherDay.Initialize(8, 25, 2006); cout << " Today is " << today.MonthIs() << "/" << today.DayIs() << "/" << today.YearIs() << endl; cout << " Another date is " << anotherDay.MonthIs() << "/" << anotherDay.DayIs() << "/" << anotherDay.YearIs() << endl; switch (today.ComparedTo(anotherDay)) { case LESS : cout << "today comes before anotherDay"; break; case GREATER : cout << "today comes after anotherDay"; break; case EQUAL : cout << "today and anotherDay are the same"; break; } return 0;}