According to Wikipedia, Calisthenics are a form of exercise consisting of a variety of simple, often rhythmical, movements, generally without using equipment or apparatus. Since programming without Visual Studio is going to be a bit challenging you can define Object Calisthenics as a programming exercise that uses simple rules to motivate you to take an object-oriented approach to programming. As an experienced developer practicing Test Driven Development I was a bit sceptical of whether I really needed those rules to be a better programmer. But to my surprise those little rules really reinforced my beliefs about building high-quality software using the principles of object-orientation, SOLID and Clean Code. So what are those rules? I won’t tell you…yet. Just come to my session and I’ll let you in on my secrets….

1. #comdaybe
Object Calisthenics
Practices for Writing Object-Oriented
Aviva Solutions
Dennis Doomen

2. Object…what?
Object Calisthenics
Object..ˌka-ləs-ˈthe-niks

3. Like this?

4. “…9 rules of thumb that will help push
your code into good object-oriented
shape...”
Jeff Bay

5. So who am I?
Principal Consultant
Aviva Solutions
Fluent Assertions
C# Coding
Guidelines
@ddoomen
TDD, DDD, BDD
Application Lifecycle
Management
Agile
XP
www.dennisdoomen.net

6. demo
One level of indentation per method
Rule 1

7. demo
One dot per line
Don’t use the else keyword
Rules 2 & 5

8. demo
Wrap all primitives and strings
…a.k.a. first-class types
Rule 3

9. demo
First-class collections
Rule 4

10. Choose names carefully
…not too short
…and…not too long
…contextual
Rule 6

11. Keep all classes small
…a.k.a. Single Responsibility Principle
Rule 7

12. No more than two instance variables
Rule 8

13. demo
No properties
Rule 9

14. demo
…no protected properties
…test data builders
…more refactoring
Final result

15. Q&A

16. Resources
• Example Code (original by Johan
Martinsson)
• Object Calisthenics (by Jeff Bay)
• C# Coding Guidelines (by me)
• www.dennisdoomen.net (by me…again )
• Agile Principles, Patterns, and Practices in
C# (by Uncle Bob)

17. Thank you!
Object Calisthenatics