Writing clean code in C# and .NET

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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.

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  • The developer
    Wrote the code
    - Was the first to see the feature
    Can validate requirments
  • So why not have better testing?
    It’s hard to find all of the scenarios
    Cost of fixing increase
  • Bad code attracts more bad code

    “It was like this when I got here”
  • Show example of not readable code
  • a.k.a spaghetti code
  • Avoid duplicate code (DRY)
  • Writing clean code in C# and .NET

    1. 1. Writing Clean Code in C# and .NET
    2. 2. About.ME • Senior Consultant @CodeValue • Developing software (Professionally) since 2002 • Writing clean code since 2009 • Blogger: http://blog.drorhelper.com
    3. 3. Let’s talk about software bugs
    4. 4. Bugs cost around $312 Billion Per Year
    5. 5. And it’s all a developer’s fault
    6. 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. 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. 8. Broken windows
    9. 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. 10. Quality == Agility • Adapt to changes • Don’t be held back by bugs • Cannot be agile without high quality code
    11. 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. 12. “Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live”
    13. 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. 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. 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. 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. 17. Comments often are used as a deodorant Refactoring, Martin Fowler
    18. 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. 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. 20. Regions == Comments
    21. 21. Naming is important d, days  daysSinceLastPayment customerPo  customerPurchaseOrder productIdString  productId genymdhms  generationTimeStamp
    22. 22. Dead Code • Code which is never run • But still has maintenance costs • Solution - delete
    23. 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. 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. 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. 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. 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. 28. Design stamina hypothesis http://martinfowler.com/bliki/DesignStaminaHypothesis.html
    29. 29. Principles of Object Oriented Design Single responsibility Open/closed Liskov substitution Interface segregation Dependency inversion www.butunclebob.com/ArticleS.UncleBob.PrinciplesOfOod
    30. 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. 31. Naming as code smell Having difficulties naming your class/method? You might be violating SRP
    32. 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. 33. Open closed principle software entities should be open for extension, but closed for modification
    34. 34. Liskov subtitution objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program
    35. 35. 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? {
    36. 36. Interface segregation Many client specific interfaces are better than one general purpose interface. http://en.wikipedia.org/wiki/Cockpit
    37. 37. Dependency Inversion Depend upon abstractions. Do not depend upon concretions.
    38. 38. Your code will change! • Requirements change • Bugs are found • New feature requests  Your design will change
    39. 39. In the beginning… Application was beautiful - then came change… • Software Rot – Duplication – Excess coupling – Quick fixes – Hacks
    40. 40. 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(); { {
    41. 41. Refactoring
    42. 42. 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/
    43. 43. Refactoring with Visual Studio
    44. 44. 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
    45. 45. 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.”
    46. 46. Don’t expect your company to force you Be a professional Care about your code
    47. 47. 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

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