oops: the harsh realities of programming · course overview complexity and the nature of...

Course OverviewComplexity and the Nature of ProgrammingOverview of Object Oriented Programming

Object Oriented Programming in C++

OOPs: The Harsh Realities of Programming

Robert Lowe

Division of Mathematics and Computer ScienceMaryville College

Robert Lowe OOPs: The Harsh Realities of Programming



Outline

1 Course Overview

2 Complexity and the Nature of Programming

3 Overview of Object Oriented Programming

4 Object Oriented Programming in C++




Preliminaries

Required MaterialsBig C++ 2nd Edition by CayHorstmannAn Account onsmc.cs.maryvillecollege.edu

Catalog Description

A continuation of Computer Science111 with emphasis on advancedprogramming features. Laboratorywork supplements and expandslecture topics and offers supervisedpractice using programming.




Recommended Supplementary Text

The C++ Programming Language 4thEdition by Bjarne Stroustrup

Written by the creator of C++Serves as a Good ReferenceVery in-depth Explanations ofThe LanguageThis should be on the bookshelfof all serious C++ programmers.




Course Goals

Gain an advanced understanding of Object OrientedProgramming.Learn to use Object Oriented Analysis and Design to buildlarge complex programs.Gain a preliminary understanding of low level programmingconcepts, especially memory addressing.Increase your knowledge of using and programming theUNIX operating system.Hone your knowledge of programming tools like make,g++, and gdb.Learn new tools, like rcs.




Grading

GradingLabs 15%Programming Assignments 50%Exams 35%




Summary of Classroom Expectations

Show up for class.Don’t cheat.Attempt all the work.Ask lots of questions.Late assignments will generally not be accepted.Don’t Panic!




Outline of Major Topics

I. Object Oriented Programminga. Classes and Objectsb. Inheritance and Polymorphismc. Overloaded Operators and Functionsd. Object Oriented Analysis and Design

II. Problem Solving Techniquesa. Recursionb. Backtracking

III. Tools and Techniquesa. gdbb. UNIX System APIc. Exceptions




Software Development Life Cycle

Programming Is:ExpensiveVery ComplexCritical

The Ninety-Ninety RuleThe first 90 percent of the codeaccounts for the first 90 percent of thedevelopment time. The remaining 10percent of the code accounts for theother 90 percent of the developmenttime.– Tom Cargill, Bell Labs

Image Source: wikipedia.org




Coping with Complexity

The Main Challenge is Dealing With ComplexityAnalyze Big TasksDecompose Big TasksEncode Tasks into Computer Code




Coping with Customers

Real world customers are not very tech savvy.Often, programs perform tasks outside of theprogrammer’s expertise.Many iterations are needed to capture requirements.Even then, requirements are typically vague!




What Makes Programming Difficult

ComplexityVague and Underdeveloped RequirementsTime PressureOne-Off Nature of Programs




Programming Paradigms

Programming paradigms represent ways of thinking andmethods of decomposition.Imperative Programming All statements are direct commands

which alter the program’s state. (ex. Assembly andALGOL)

Procedural Programming Programs are decomposed intosub-routines. (ex. C and Pascal )

Functional Programming Computation is represented asmathematical functions. (ex. LISP and Erlang)

Object Oriented Programming Programs are decomposed intoobjects. (ex. C++ and C#)




Effective Use of a Programming Language

General Tips for Programming Language UseA programming language is a formal representation ofideas.Think first and then code!Use a language that is well suited to the task at hand.Learn the idioms of your language.Always use the language to express, rather than obscure,your intentions!




Objects and Classes

Object An entity with state and behavior. (Instance ofClasses)

VariablesConcrete Objects

Class A collection of objects with identical attributes andbehaviors. (Definition of Objects)

Member FunctionsMember VariablesAbstract Entity




Parts of Speech and OOP

Nouns Objects and ClassesVerbs Member Functions

Adjectives Member Variables




An OOP Translation Example

1 Write some sentencesdescribing the robot and itsstate.

2 Write some sentencesdescribing what the robotcan do.

3 Sketch out what a robotclass may look like.




Four Major Principles of Object Oriented Programming

Encapsulation Attributes and state are contained within objectsand access to these attributes are restricted.

Abstraction The inner workings of the objects are hidden.Inheritance Objects types can be derived from, and extend,

other object types. (Is-A relationship)Polymorphism Objects can be referenced by different types,

and they still behave correctly when treated asinherited types.




Goals for Effective Object Oriented Programming

Your programs should be clear in intention.Objects should be cohesive.Objects should not be tightly coupled with other objects.




Class Declaration

class name{public:

//public methodsprotected:

//protected variables and methodsprivate:

//private variables and methods};




Access Modifiers

public Accessible to code inside and outside of the class.

MethodsConstructorsDestructor

protected Accessible to code within the class andsub-classes. (A big part of inheritance.)

Variables (with great care)Methods

private Accessible only to code within the class.VariablesMethods




Constructors and Destructors

ConstructorsInitializer for a classCan be overloadedDeclared with same name as an object: name();No return type

DestructorCleans up after an object.Used frequently with dynamic memory.Named: ∼name();




Member Initialization Lists

Member initialization lists can be used when simply copyingvalues from constructor arguments. They are an absolute mustwhen working with references!

name(int x, int y) : x(x), y(y){//constructor code

}




Constructor and Destructors Best Practices

Unless you really know what you are doing, constructorsshould be public.You should provide at least:

1 No-Argument constructor: name();A copy constructor: name(name &c);If initial conditions make sense, you should have aconstructor which allows them to be set.

If you use any dynamic memory, you must create adestructor.




Putting it All Together

Let’s implement our robot class!


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