Webcast: Identify and Correct Common Code Smells

Identify and Correct Common Code Smells 11/12/2014 http://submain.com/webcasts/identify-and-correct-common-code-smells/ for the webcast recording and slides download

Webcast Housekeeping Audio  Connect viaVoIP (default)  Plug in a headset or turn up your speakers  Select “User Mic and Speakers” in Camera andVoice  Connect via Phone  Select “Dial In” in Audio Options  Call 1 (206) 453-2087 (see confirmation email for local numbers)  PIN: 685568# Asking A Question  Use the Chat window in the bottom left corner  Questions will be addressed at the end of the webcast Recording  A recording download link will be sent to all registrants within a few days 11/12/2014 Copyright © SubMain 2014 Slide 2

Steve Smith Pluralsight Author  SOLID Principles, Design Patterns  DDD, N-Tier Architecture  Kanban, Web PerformanceTuning/Testing  Refactoring and Code Smells Blog  Ardalis.com More  http://about.me/stevenasmith 11/12/2014 Copyright © SubMain 2014 4 @ardalis StevenAndrewSmith stevenandrewsmith

Kent Beck’s Rules of Simple Design Well-designed code should:  Run all the tests (successfully)  Contain no duplicate code  Express all the ideas its authors wish to express  Minimize classes and methods 11/12/2014 Copyright © SubMain 2014 Slide 8

Code Smell: Long Method Prefer short methods to long methods  Smaller methods can have more descriptive names  Smaller methods are easier to understand at a glance  Less likely to duplicate code between small methods Strive for no more than 10 lines of code per method Do not tolerate methods that do not fit on one screen 11/12/2014 Copyright © SubMain 2014 Slide 9

Code Smell: Large Class Similar to Long Method Usually violates Single Responsibility Principle May have  Too many instance variables  Too many methods  All of the above Typically lacks cohesion  Several classes baked into one 11/12/2014 Copyright © SubMain 2014 Slide 11

Code Smell: Primitive Obsession Abusing primitives instead of using better abstractions Less intention-revealing Leads to scattered business logic  Guard clauses  Validation 11/12/2014 Copyright © SubMain 2014 Slide 12

Example: Primitive Obsession // method call relying on primitives only AddHoliday(7,4); // use a higher level type Date independenceDay = new Date(7,4); AddHoliday(independenceDay); 11/12/2014 Copyright © SubMain 2014 Slide 14

Example: Primitive Obsession // go even further public class July { private const int _month = 7; public static readonly Date Fourth { get { return new Date(_month, 4); } } } AddHoliday(July.Fourth); 11/12/2014 Copyright © SubMain 2014 Slide 15

Example: Primitive Obsession // method call relying on primitives TransferFunds(23423, 23434, 48432); // refactored to be more clear and use higher level objects Account transferFrom = _accountRepository.Get(23423); Account transferTo = _accountRepository.Get(23434); var transferAmount = new Money(48432, Currency.USD); TransferFunds(transferFrom, transferTo, transferAmount); 3/25/2014 Copyright © SubMain 2014 Slide 19

Code Smell: Data Clumps Sets of data items that are always used together, but are not organized together Similar to Primitive Obsession, but always deals with several items Frequently give rise to long parameter lists (another smell) 11/12/2014 Copyright © SubMain 2014 Slide 21

Example: Data Clumps // data clumps on an order Order.CreditCardName = creditCardName; Order.CreditCardNumber = creditCardNumber; Order.ExpiresMonth = creditCardMonth; Order.ExpiresYear = creditCardYear; Order.SecurityCode = creditCardSecurityCode; 11/12/2014 Copyright © SubMain 2014 Slide 22

Example: Data Clumps // data clumps on an order Order.CreditCardName = creditCardName; Order.CreditCardNumber = creditCardNumber; Order.ExpiresMonth = creditCardMonth; Order.ExpiresYear = creditCardYear; Order.SecurityCode = creditCardSecurityCode; // refactored by Extracting a new CreditCardInfo class CreditCardInfo cardInfo = new CreditCardInfo( creditCardNme, creditCardNumber, creditCardMonth, creditCardYear, creditCardSecurityCode); Order.CreditCard = cardInfo; 11/12/2014 Copyright © SubMain 2014 Slide 23

Code Smell: Poor Names Names should: Be descriptive Be at appropriate abstraction level Use standard terms Be unambiguous Avoid encodings Describe side effects Be longer when scope is large 11/12/2014 Copyright © SubMain 2014 Slide 24

Example: Poor Names public static List<int> Generate(int n) { var x = new List<int>(); for (int i = 2; n > 1; i++) for (; n % i == 0; n /= i) x.Add(i); return x; } 11/12/2014 Copyright © SubMain 2014 Slide 25

Example: Poor Names public static List<int> GeneratePrimeFactorsOf(int input) { var primeFactors = new List<int>(); for (int candidateFactor = 2; input > 1; candidateFactor++) while (input % candidateFactor == 0) { primeFactors.Add(candidateFactor); input /= candidateFactor; } return primeFactors; } // Usage: var factors = GeneratePrimeFactorsOf(input); 11/12/2014 Copyright © SubMain 2014 Slide 26

Example: Inappropriate Abstraction Level public class User { public string UserName { get; set; } public static int GetTotalUserCountInDatabaseTable() { throw new NotImplementedException(); } public static SqlDataReader GetDataReaderWithRoles(string userName) { throw new NotImplementedException(); } } 11/12/2014 Copyright © SubMain 2014 Slide 27

Example: Inappropriate Abstraction Level public class User { public string UserName { get; set; } public IEnumerable<Role> IsInRoles() { throw new NotImplementedException(); } } 11/12/2014 Copyright © SubMain 2014 Slide 28 public class SqlUserRepository { public int TotalUserCount() { throw new NotImplementedException(); } public IEnumerable<Role> UserIsInRoles(string userName) { throw new NotImplementedException(); } }

What is CodeIt.Right  Code Quality Analysis and Metrics  Automated Code Review process  Automated way to discover and fix code smells  Automatic and safe refactoring of issues into conforming code  Ensure your code adheres to (your) predefined design requirements and best coding practices 11/12/2014 Copyright © SubMain 2014 30

What is CodeIt.Right - continued Instant Code Review – real-time code checking OnDemand Analysis Source Control Check-In Policy Build Process Integration Hundreds of rules  Security, Performance, Usage, Design, Maintainability, Exception Handling, Globalization, Async, and more 11/12/2014 Copyright © SubMain 2014 31

Q&A Questions? Email - customer-service@submain.com Video - submain.com/codeit.right/video Download the free CodeIt.Right trial at submain.com/codeit.right 11/12/2014 Copyright © SubMain 2014 33 1 (800) 936-2134 http://submain.com/webcasts/identify-and-correct-common-code-smells/ for the webcast recording and slides download

Webcast: Identify and Correct Common Code Smells

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Webcast: Identify and Correct Common Code Smells