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

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11/12/2014 Copyright © SubMain 2014 Slide 2

Introduction
Presenter
Steve Smith
Microsoft MVP, RD
CTO, Falafel Software
(g)host
Serge Baranovsky
Chief Strategy Officer,
SubMain
11/12/2014 Copyright © SubMain 2014 3

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
@ardalis
StevenAndrewSmith
stevenandrewsmith

What are ‘Code Smells’ ?

Bad Smells in Code
Described by Kent Beck and Martin Fowler in
Refactoring Fundamentals
Intentionally vague term
Context-dependent; use your judgment

Principle of Least Surprise
Design your API to behave as programmers would
expect

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

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

Example: Long Method

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

Code Smell: Primitive Obsession
Abusing primitives instead of using better
abstractions
Less intention-revealing
Leads to scattered business logic
 Guard clauses
 Validation

Example: Primitive Obsession
// method call relying on primitives only
AddHoliday(7,4);

// method call relying on primitives only
AddHoliday(7,4);
// use a higher level type
Date independenceDay = new Date(7,4);
AddHoliday(independenceDay);

// 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);

// method call relying on primitives
DrawLine(5,20,25,40);

DrawLine(5,20,25,40,0,0,255);

TransferFunds(23423, 23434, 48432);

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);

Primitive Obsession Common
Examples
Phone Numbers
Social Security Numbers
ZIP/Postal Codes
Money
Age
Temperature
Address
Credit Card Information

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)

Example: Data Clumps
// data clumps on an order
Order.CreditCardName = creditCardName;
Order.CreditCardNumber = creditCardNumber;
Order.ExpiresMonth = creditCardMonth;
Order.ExpiresYear = creditCardYear;
Order.SecurityCode = creditCardSecurityCode;

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;

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

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;
}

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);

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)
{
}
}

Example: Inappropriate Abstraction Level
public class User
{
public string UserName { get; set; }
public IEnumerable<Role> IsInRoles()
{
}
}
public class SqlUserRepository
{
public int TotalUserCount()
{
}
public IEnumerable<Role> UserIsInRoles(string userName)
{
}
}

How CodeIt.Right Helps

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

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

Demo
Discover and Fix Code Smells
Coding Pattern Examples
 ISerializable/Custom Serialization
 Dispose/Finalize

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
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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