Maintaining the product is one (if not the most) expensive area of the overall product costs. Writing clean code can significantly lower these costs, making it more efficient during the initial development and results in more stable code. In this session participants will learn how to apply C# techniques in order to improve the efficiency, readability, testability and extensibility of code.

1. Writing Clean Code in C# and .NET

2. About.ME
• Senior Consultant @CodeValue
• Developing software (Professionally) since 2002
• Writing clean code since 2009
• Blogger: http://blog.drorhelper.com

3. Let’s talk about software bugs

4. Bugs cost around $312 Billion Per Year

5. And it’s all a developer’s fault

6. The cost of fixing bugs
1 2 10
20
50
150
RQUIRMENTS DESIGN CODE DEV T ACC T OPERATION
[B. Boehm - ICSE 2006 Keynote Address]

7. High quality code is:
• Easy to read and understand
• Impossible to hide bugs
• Easy to extend
• Easy to change
• Has unit tests
Be a proud of your code

8. Broken windows

9. The cost of owning a mess
0
10
20
30
40
50
60
70
80
90
100
Productivity
Productivity
[Robert Martin – “Clean Code”]

10. Quality == Agility
• Adapt to changes
• Don’t be held back by bugs
• Cannot be agile without high quality code

11. How a developer spends his time
60% - 80% time spent in understanding code
So make sure your code is readable
But what is a readable code?

12. “Always code as if the guy who ends up
maintaining your code will be a violent
psychopath who knows where you live”

13. Megamoth
Stands for MEGA MOnolithic meTHod.
Often contained inside a God Object, and
usually stretches over two screens in height.
Megamoths of greater size than 2k LOC have
been sighted. Beware of the MEGAMOTH!
http://blog.codinghorror.com/new-programming-jargon/

14. Write short methods – please!
• It’s easier to understand
• Performance won’t suffer
• Avoid mixing abstraction layers
• Enable re-use
• Also write small classes

15. How can we recognize bad code?
• You know it we you see it
• You feel it when you write it
• You get used to it after a while 
• known as Code Smells

16. Code Smells
• Duplicate code
• Long method
• Large class
• Too many parameters
• Feature envy
• Inappropriate intimacy
• Refused request
• Lazy class/Freeloader
• Contrived complexity
• Naming!
• Complex Conditionals
• And more…
http://en.wikipedia.org/wiki/Code_smell

17. Comments often are used as a deodorant
Refactoring, Martin Fowler

18. Comments are a dead giveaway
• If explains how things done means that the
developer felt bad about the code
• “Code title” – should be a method
• Commented Old code – SCM
Good comments exist in the wild – but rare

19. http://stackoverflow.com/questions/184618/what-is-the-best-comment-in-
source-code-you-have-ever-encountered
/// <summary>
/// Gets or sets the name of the first.
/// </summary>
/// <value>The name of the first.</value>
public string FirstName
}
get { return _firstName; }
set { _firstName = value; }
{
/** Logger */
private Logger logger = Logger.getLogger();
/// <summary>
/// The possible outcomes of an update
operation (save or delete)
/// </summary>
public enum UpdateResult
}
/// <summary>
/// Updated successfully
/// </summary>
Success = 0,
/// <summary>
/// Updated successfully
/// </summary>
Failed = 1
{
//private instance variable for storing age
public static int age;
// Always returns true.
public bool isAvailable()
}
return false;
{

20. Regions == Comments

21. Naming is important
d, days  daysSinceLastPayment
customerPo  customerPurchaseOrder
productIdString  productId
genymdhms  generationTimeStamp

22. Dead Code
• Code which is never run
• But still has maintenance costs
• Solution - delete

23. Undead Code
Dead code that you’re afraid to delete
- “I might need this…”
geek-and-poke.com/
// UNUSED
// Separate into p_slidoor.c?
#if 0 // ABANDONED TO THE MISTS OF TIME!!!
//
// EV_SlidingDoor : slide a door horizontally
// (animate midtexture, then set noblocking line)
//

24. Avoid duplicate code (DRY)
“Every piece of knowledge must have a
single, unambiguous, authoritative
representation within a system”
The Pragmatic Programmer: Dave Thomas, Andy Hunt

25. public bool HasGroup(List<Token> tokenList){
for(Token token : tokemList){
if(token.get_group() != null) {
return true;
{
{
return false;
{
public Group GetValidGroup(List<Customer> customers){
for(Customer customer : customers){
Group group = customer.get_group();
if(group != null) {
return group;
{
{
return null;
{

26. Good code start with good design
Bad DesignGood design
RigidLoosely coupled
FragileHighly cohesive
ImmobileEasily composable
ViscousContext independent
It’s all about dependencies
• In .NET Reference == dependency
• Change in dependency  change in code

27. This is not OOP!!!
public class Record_Base
{
public DateTime RecordDateTime
{
get { return _recordDateTime; }
set
{
if (this.GetType().Name == "Record_PartRegister")
_recordDateTime = value;
else
throw new Exception("Cannot call set on RecordDateTime for table " + this.GetType().Name);
}
}
}
http://thedailywtf.com/Articles/Making-Off-With-Your-Inheritance.aspx

28. Design stamina hypothesis
http://martinfowler.com/bliki/DesignStaminaHypothesis.html

29. Principles of Object Oriented Design
Single responsibility
Open/closed
Liskov substitution
Interface segregation
Dependency inversion
www.butunclebob.com/ArticleS.UncleBob.PrinciplesOfOod

30. Single responsibility
A class should have one, and only one,
reason to change.
http://www.amazon.com/Wenger- 16999-ssiwS-efinK-
B/pd/tnaiG001 DZTJRQ/

31. Naming as code smell
Having difficulties naming your class/method?
You might be violating SRP

32. public interface ITimerService
{
IDisposable SetTimout(long durationMilliSeconds, Action callback);
Task Delay(TimeSpan delay, CancellationToken token);
void KillLastSetTimer();
}
public interface IDispacherTimerService : ITimerService
{
long GetMilisecondsFromLastStart();
}
public interface IElapsedTimerService : ITimerService
{
void SetTimout(long durationMilliSeconds, Action<TimeSpan> callback);
}

33. Open closed principle
software entities should be
open for extension,
but
closed for modification

35. Liskov subtitution
objects in a program should
be replaceable with instances of their
subtypes
without altering the correctness of that
program

36. LSP smell - look for type checking
void ArrangeBirdInPattern(IBird aBird)
}
var aPenguin = aBird as Pinguin;
if (aPenguin != null)
}
ArrangeBirdOnGround(aPenguin);
{
else
}
ArrangeBirdInSky(aBird);
{
// What about Emu?
{

37. Interface segregation
Many client specific interfaces are better than
one general purpose interface.
http://en.wikipedia.org/wiki/Cockpit

38. Dependency Inversion
Depend upon abstractions.
Do not depend upon concretions.

39. Your code will change!
• Requirements change
• Bugs are found
• New feature requests
 Your design will change

40. In the beginning…
Application was beautiful - then came change…
• Software Rot
– Duplication
– Excess coupling
– Quick fixes
– Hacks

41. public override void HandleActionRejected(User from, reason reason)
}
Logger.Info("HandleActionRejected - user:{0}", from.Id);
/*foreach (var user in UserRepository.GetAllUsers)
}
Client.SendInfo(user, from, reason);
{ */
//2.2
Events.Users.Value = new UserData
}
SessionId = CurrentSession.Id,
HaveIInitiated = true,
OtherUser = from,
StartCallStatus = Events.ConvertToCallStatus(answer)
{;
UserRepository.Remove(from, reason);
if(UserRepository.IsEmpty())
}
Exit();
{
{

42. Refactoring

43. Refactoring
“a disciplined technique for restructuring
an existing body of code, altering its
internal structure without changing its
external behavior”
- Martin Fowler
http://refactoring.com/catalog/

44. Refactoring with Visual Studio

45. Code reviews
Can catch up to 60% of defects
Effective code reviews are:
• Short – don’t waste time
• Constructive
• Avoid emotionally draining arguments
Everybody reviews and everybody is reviewed

46. No quality has very high cost
Never have time to do it,
but always have time to re-do it.
Explain why this feature takes so much time
“You rush a miracle man,
you get rotten miracles.”

47. Don’t expect your company to force you
Be a professional
Care about your code

48. Improve your code
• Start as soon as you can
• Don’t compromise
Schedule time for quality
–Improve existing code
–Make it work, then make it better
49