How object oriented are you feeling today?
2 likes1,208 views
Krzysztof Jelski presented on object-oriented design principles known as the "Nine Rules". The presentation included an overview of each rule, examples of how they impact design, and a discussion of which rules were easiest/hardest to follow and had the biggest impact. The rules focused on concepts like single responsibility, encapsulation, and composition over inheritance. Jelski also demonstrated applying the rules through a bank account management kata example.
How object oriented are you feeling today?
- 1. How Object-Oriented Are You Feeling Today? Software Craftsmanship 2011 26th May, Bletchley Park Krzysztof Jelski
- 3. Agenda INTRO WRAP-UP
- 4. The Nine Rules 1. UseOnelevelofindentationpermethod 2. Don'tusetheelsekeyword 3. Wrapallprimitivesandstrings 4. Useonlyonedotperline 5. Don'tabbreviate(one足ortwo足wordsnames) 6. Keepallentitiessmall(50lines/class,10classes/package) 7. Don'tuseanyclasseswithmorethantwoinstancevariables 8. Usefirstclasscollections 9. Don'tuseanygetters,settersorproperties
- 5. Bank Accounts Kata Thinkofyourpersonalbankaccountexperience Whenindoubt,goforthesimplestsolution
- 6. Features Deposit,Withdrawal Transfer AccountStatement(date,amount,balance) Statementprinting Statementfilters
- 7. You can start with BankAccountsKatasamplecode http://bit.ly/jtOP6F ifyouneedjoda足time http://bit.ly/kSpwNj
- 8. Wrap-up Whichrules: weresimplesttofollow? hardest? hadbiggestimpactondesign? youthinkyoucoulduseinproduction?
- 9. Rule 1: Use One Level of Indentation per Method Method足>doesexactlyonething Reuse Readability Implementationmatchesname足>easiertofindbugs
- 10. Rule 2: Don't Use the else Keyword Simplecases足>guardclauses,earlyreturns Complexcases足>polymorphism(Strategy,NullObject)
- 11. Rule 3: Wrap All Primitives and Strings Expressintent Type足safe Placeforbehaviour
- 12. Rule 4: Use Only One Dot per Line Placeresponsibilitiesproperly TheLawofDemeter yourtoys toysthatyoumake toyssomeonegivesyou
- 13. Rule 5: Don't Abbreviate Removeduplication Placeresponsibilitiesproperly
- 14. Rule 6: Keep All Entities Small SingleResponsibilityPrinciple Cohesivepackages
- 15. Rule 7: Don't Use Any Classes with More Than Two Instance Classcohesion Variables Findcommonalityofinstancevariables ObjectModeldecomposition
- 16. Rule 8: Use First-Class Collections Homeforcollection足relatedbehaviour
- 17. Rule 9: Don't Use Any Getters/Setters/Properties Strongencapsulationboundaries Tell,don'task
- 18. References ObjectCalisthenics,JeffBayin:TheThoughtWorksAnthology, PragmaticBookshelf2008. Pics http://www.flickr.com/photos/jiheffe/3462940215/ http://www.flickr.com/photos/singapore2010/4916726882