LESSON 1 – INTRODUCTION

Unit 6 - Software Design and Development

What is covered in this session Introduction to unit and reference sources

Schedule for assignments

Introduction

From this unit the learner will:

1. Know the features of programming languages

2. Understand the principles of software design

3. Be able to use tools to demonstrate software designs.

Assignment Schedule

Lesson 3 – Assignment 1 Which language? -Covers P1, P2, P3, P4

Around week 7 - Assignment 2 Design workshop- Covers P5, M1, D1

~ Week 12 – Assignment 3 Good Design!-Covers P6, M2, D2

Some useful references

Pilone & Miles, Head First Software

Development, O’Reilly Media, USA,

2008,

Anderson et. al,

Information

Technology Level 3

Book 1 pp 161 –

188, PearsonUK,

2010

https://www.codecademy.com/

Where is IT used?

List as many industries as you can where IT is used.

Football

Architect

Dairy farm

Fire and Rescue

Botanic Garden

Magazine

Car manufacturer

Chocolate factory

http://www.bbc.co.uk/programmes/b00zsc2s/clips

Problem

Firemen (farmers, footballers, car designers etc., etc ) are not programmers

Programmers are not firemen ((farmers, footballers, car designers etc., etc )

Issues caused by: Poor understanding of user need

Poor planning

This unit..

focuses on the design and development process

systems development life cycle

looks at programming concepts

examines the business context within which solutions can be developed

explores the tools that can be used to demonstrate software designs

Writing computer programs

Programmers use an IDE (Integrated Development Environment) to enter their code.

It is possible to use a text editor such as Notepad to enter your code but this is difficult and requires specialist knowledge.

Writing computer programs

Examples required in this unit

Use an IDE from Microsoft called Visual Studio 2015

Use VB.net as main programming language.

Predominantly Form based programs.

Form based programs use a GUI (graphical user interface).

Know the features of programming languages

Programming paradigms

Types of language

Reasons for choice of language

Features

Data types

Programming paradigms

Difficult to spell

Difficult to pronounce

Meaning?

Greek – paradeiknunai – to show side by side - A typical example or pattern of something; a pattern or model

Style (or different approaches) of programming

Programming

Computer = hardware + software

Hardware

So much twisted metal

Software

Firmware

Operating systems

Applications

i.e. programs

Programming

Computer reads binary (or as the computer sees it…

010000110110111101101101011100000111010101110100011001010111001000100000011100100110010101100001011001000111001100100000011000100110100101101110011000010111001001111001

Programming

Use symbolic languages with human-like statements

Different approaches – paradigms (011100000110000101110010011000010110010001101001011001110110110101110011)

Programming paradigms

a fundamental style of computer programming, a way of building the structure and elements of computer programs.

some programming languages are designed to follow only one paradigm, while others support multiple paradigms.

http://en.wikipedia.org/wiki/Programming_paradigm

E.g. Unit 16 Procedural programming

Programming Paradigms

three main types:

Procedural

Object oriented

Event Driven

Others include:

• Scripted

• Visual

Can you name a

visual programming

language?

Other languages

E.g. HTML

A mark-up language, not a true programming language.

Does not contain instructions to control the flow of the program, such as decision statements. (e.g. if..;if..else;case)

Task 1

Working in pairs – produce a set of PowerPoint slides which show examples of code written in different languages.

Extension: Try and find the same examples in the different languages.

The languages chosen must include: Python, VB.net, Javascript.

You need to include at least 5 different languages.

For each one, state the language name, example code, what the example code does and what paradigm (see below) you think applies to the language.

Possible paradigms Procedural. Event Driven. Object Orientated (OOP).

Task 1a Programming paradigms

Research the languages’ popularity and add this to the slide for each language you have chosen.

Record the source of this information.

Visual Programming

any programming language that lets you develop programs by manipulating program elements graphically rather than textually.

Visual Programming

also known as dataflow or diagrammatic programming.

Task 2 Visual Programming

access scratch here:

http://scratch.mit.edu/

Make the cat walk to the right of the screen,

turn around and walk to the left of the screen then turn around and repeat.

Ext – make the cat say hello when it reaches each side, vary the speed.

Procedural Programming

a linear process where each program statement is executed line by line, one after the other.

The program can be compiled/managed or be scripted.

Some examples of procedural programming languages are :

1. C (because it comes after B) 2. Pascal (named after a French mathematician)

3. FORTRAN (formulated translation) 4. COBOL (Common Business Oriented

Language)

Procedural Programming

Advantages –

Good for general programming.

Can be scripted.

Good level of control, can be multi-platform.

Has a Portable Source Code.

Disadvantages:

There are a lot of procedural languages, and you cannot learn them all, usually you learn one well.

Large programs can run very slowly.

Need to develop in a methodical way and test frequently.

Testing can be slow as all processes need to be re-tested each time even though they have been proven to work.

Object Oriented Paradigm (OOP)

a programming model organized around:

objects rather than "actions" and

data rather than logic.

It uses the system of classes and objects, a class may hold many objects

Examples: C++, C#, Python, vb.net, Java

Basic OOP

Objects have to be instantiated (Created) using designs (Classes) .

Objects encapsulate the data and functions (methods) needed to manage the data.

The designs (classes) take the most time to create.

They offer great flexibility in program development and maintenance.

Basic OOP

Created in the 1980’s

Breaks the task into modules called classes

Classes are easier to modify

Improved security of data (hidden data)

Easy to add functions (classes)

Follows a bottom-up approach

Object Oriented Paradigm

Advantages:

Has a clear structure good for defining data types

easy to maintain and modify existing code new objects can be added by copying and slightly changing

previous code allows faster development.

Low cost due to reusing code

Disadvantages:

Complex thought process difficult for some people to learn / get used to.

Large Program size slower as more instructions must be executed.

Event Driven Programming Paradigms

for example, an object is clicked on and it triggers an event.

used for things like renting out cars

a GUI would be used

when the user clicked on a button an event would be triggered detailing which cars were still available to rent

Examples: C, C++, C#

Event Driven Programming Paradigms

Advantages: Flexibility Used a lot with modern GUI programs allows for more interactive programs. Disadvantages: A mixture of object oriented and procedural

programming – similar limitations Requires large amount of processing power An extra layer of complexity Less easy to follow the logic

TOOLS

CLI – Command Line Interface.

In the past all programs were written using a CLI, one line at a time!.

IDE – Integrated Development Environment.

Most programs are now written using an IDE, VS201x, Eclipse, PyCharm, PHPStorm etc.

CASE – Computer Aided Software Engineering.

Integrated Development Environment

Everything needed to write a program

Editor – for writing instructions

Additional tools e.g. pop-up help

Compiler – converts program to machine code

Windows forms editor

Creates Windows forms and controls (buttons, text boxes, check boxes etc)

Debugger

CASE tools

Computer Aided Software Engineering

Used in large software development projects

Automates parts of the process

Assists in creation of design diagrams

Structure charts

Data flow diagrams (DFDs)

Entity relationship models (ERMs)

Case Tools

Unified Modelling Language (UML)

CASE tools, Class diagram

CASE tools, sequence diagram

Programming generations

1842

calculation

of

Bernoulli

numbers

Ada

Lovelace

1940s

Great deal

of effort,

Error-

prone

Programming generations

High-level languages use notation which is more familiar to

humans: mathematical or spoken/written language.

Task 3

Using the slides created in task 1 –

Research each language in your slides and add the generation of languages they belong to:

1gl,

2gl,

3gl,

4gl,

5gl

Homework: - submit to TurnitinL3U06H1PeterPan2016

Prepare a presentation, including speaker notes, to explain to trainees the typical applications for the major programming paradigms. Give examples of the types of program that each paradigm should be used to write. Describe the limitations of each paradigm.

Include the following paradigms:

Procedural

Object-oriented

Event-driven