Design Part II Getting Ready to Build!

transcript

Kunal Johar Design Part III 1

Kunal JoharCSCI 4243 (Senior Design)

The George Washington University

Where are We in Design?

• Specifications Document Development– Idea / Problem Statement– High Level Requirements– Use Cases– Functional / Non-Functional Requirements– Components Needed– Workflow

Where are We in Design?

• UI / Mockups

• Final Workflow

• Data Structures / Algorithms

• Third Party APIs

Where Are We in Development?

• Bootcamp I Complete

• Bootcamp II in Progress

What is Next?

• Design Part III– Coding Structure– Repository Setup– Test Plan– Development Task List / Estimation

• Bootcamp II

• 30% Demo!

Good Code Structure

• Why Bother? What are some traits?

Good Code Structure

• Remember Shop Vote?

Shop Vote Code Structure

• How would you lay out your code?

Which Is Better?

- Vote.java

- Images.java

/Logic

- Vote.java

- Images.java

/Configuration

- General.java

- Votes.java

- Data.java

- Logic.java

- Configuration.java

/Images

- Data.java

- Logic.java

GeneralConfiguration.java

Attributes of Good Structure

• Well defined, yet simple

• Intuitive to you and other developers

• Extensible– Supports additions without needing to create

a new “structure”

• Good News: There are techniques for this!

Naming Conventions

• CONSTANTS _constants

• VariableNaming variableNaming

• Methods / Procedures()

• Classes

• Sounds a bit OO– How about C? Or LISP?

Naming Conventions

• Why Have Them?– Make code readable– Common construct for developers of a

language– Fundamental to the success of an open

source project

– Makes code safer! Really.http://www.joelonsoftware.com/articles/Wrong.html

Where To Start

• Find a code writing style guide– Java (http://www.oracle.com/technetwork/java/codeconv-

138413.html)

– Javascript (http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml)

– C# (http://www.akadia.com/services/naming_conventions.html)

– Haskell (http://urchin.earth.li/~ian/style/haskell.html)

– C / Systems Code (http://www.seas.gwu.edu/~gparmer/csg.pdf)

Read Their Rules

• Capitalization Style– PascalCase, camelCase, UPPERCASE

• Notation– Brief: SetScrollX– Verbose: SetHorizontalScrollPosition– Hungarian: fBankBalance,

studentCurrentStudent

Add Your Rules

• Special Classes

• Folder Naming Structure

• Packages / Name Spaces

• What is a Name Space?– edu.gwu.cs.BiFi

Shop Vote

• C# Language

• Server Side and iPhone Application

• “Simple” application– How would you lay out the server side?– How about the client side?

Shop Vote

• Even Simple Applications Need Structure

Intro to Design Patterns

• Idea that code creation follows patterns depending on what code is for

• Widely accepted concepts on how to structure code

• Implemented across standard libraries for countless langages

Naming Conventions on Steriods

• Creational patterns– Builders, Factories, Singleton

• Structural patterns– Wrappers, Bridges, Proxies

• Behavioral Patterns– Iterators, Observers, States

• Concurrency Patterns– Lock, Monitor, Thread, Pool

Comments

• Intuitive code means fewer comments– Good naming conventions– Avoid complex code

– Loosely couple components• What does this mean?

Documentation

• Comment public properties / public methods

• Use a documentation tool– http://www.stack.nl/~dimitri/doxygen/

Setup a Repository

• Git, SVN, Mercurual

• Herve spoke to you about this a few weeks ago

• No excuse for not having one setup

• Decide when you will check in code– Only working code?– Only after full modules are built?– Make sure you comment your check ins

In Class Exercise

• Write out the authentication class of the web service

• Then write a set of unit tests to confirm the functionality works

• Use realistic pseudocode

Let’s Take a Look at ShopVote

• Model View Controller

• Makes Unit Testing a Lot Easier

• Two repositories– Server side – Client side (phone)

• [Link to code spaces]

Project Management Planning

• Better idea of difficulty of your project after Bootcamp I and II

• But to get to 30% we need a Bootcamp III

• 30% - 100% can then be defined

Plan a Daily Activity

• What to develop first?– The hard stuff

• What to develop last?– Get everything working– Make everything look good– Get a few things to look great

http://www.joelonsoftware.com/articles/fog0000000018.html

Filling in the Empty Shell

• Build a Shell of Major Functionality

• Fill in the shell with code

• Use Unit Tests and Mock Objects to test subcomponents– These won’t catch all errors but will help

narrow them down

Unit Testing

• Ensure baseline functionality works• Speeds up Debugging

• Does not require custom tools– Method stubs with expected return values

• Tools Do Help Though – JUnit / JMock– NUnit

Project Management Tools

• “Task List” manager• Time Estimation

• MS Project– Large learning curve, very powerful– Useful for large projects with large teams (building an airplane)

• Assembla, Google Code, Microsoft CodePlex– Simpler task tracking “ticketing” tools– Bug Tracking / Feature Tracking– Integrate with repository

Bootcamp III

• What are the remaining challenging parts of this project?

• What are the frameworks / APIs that need setup

• What do you have the least control over?

ShopVote Bootcamp III

30% - 100%, 110%

• Look at HW5.pdf for remaining tasks– Get the framework done

• E.g. Site map, login screens• These are easier to do now than later

– Look at your workflow steps with no dependencies

• Integrate components that depend on them• Repeat

Time Estmiation

• For each task– Write a description– Write a test plan to ensure results work– Estimate Time

• Time = (Coding + Testing + Integration)*P

• P = Polish, which means 3x your expected effort

Task Strategy

• For each major work flow create a single large task– Break each task into sub tasks of 4-6 hour

blocks

– Bootcamp tasks are all resolved so these remaining tasks are manageable chunks

• (Bootcamp tasks can be dozens of hours each)

What can you do in 4 hours?

• Code the front end of a single UI form

• Code the backend of a single UI form

• Develop a handful of API calls

• Input a medium (15 table) database scheme and map it to code

What can you do in 4 hours?

• Nothing if there are even minor distractions

• Nothing if you run into a nasty runtime error

• Nothing if you focus too hard on a minor problem (repositioning controls on a resize)

Work Plan

• You know how you work besthttp://www.paulgraham.com/makersschedule.html

• I recommend– 2-4 hours of coding per day– 1 day off per week– 1 marathon coding session per week– 4 hours, 1 hours testing, 3 hours fixing,

1 hour refactoring (why?)

Formulate Task List

• [Code Spaces Link]

• How long do you think each task should take us?

• Let’s talk about how long they really took us

In Class Exercise

• Start work on your coding plan

• Find a naming convention

• Determine initial directory structure

• Determine Bootcamp III tasks

Discipline + Good Code Structure

• Structure alone is insufficient

• We can’t forget good general coding rules

http://developerart.com/publications/4/wise-programming-techniques-for-writing-quality-code

Avoid Quick Hacks

• Y = Z/N

• Transform it to

If (N == 0) {Z=0;N=1; Y= Z/N}

Write Self-Explanatory Code

• SendThumbnailToAmazonS3(image);

• SendPushNotifications(contacts[], message){ foreach (contact c in contacts) SendPushNotification(message, c.DeviceID)}

Avoid Showing Off

• A = A ^ BB = A ^ B

• A = A ^ B

Avoid Dense Code Blocks• Acc[categoryC] += GetUniqueHours(start, end) * 24;

categoryC = NextCategory(categoryC, lookupCodes);

TotalTime += Acc[categoryC];MaxTotalTime = Acc[PrevCategory(categoryC, lookupCodes] + TotalTime;

This is the cleanest part of a 2,000 line time sheet generator that I wrote. Updated to:

foreach (TimeSheetCategory tc in TimeSheetCategories){ decimals timeInDays = GetTimeForCategory(start, end, tc); TotalTime += timeInDays; TotalTimePlusOverhead += timeInDays * 2;}

Avoid Duplicative Functionality

• Windows APIs– ShellExecute– ShellExecute32– ShellExecuteEx– ShellExecuteEx32– ShellExecute64

Other Tips

• Avoid “magic constants”– Place all constants in a properties or config file / class

– Keep related code together

– Strive for loose coupling• What does this mean?

– Optimize last!

What Are You Here For?

Design Part II Getting Ready to Build!

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