SOLID principles presentation and few additional words about DRY, KISS, YAGNI

1. Joanna Lamch
SOLID

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

4. Problems
• Does our code solves challenges and
business problems that it should
• Is our code human readable
• Is our code maintainable
• Is our code extensible, scalable
• Is our code granular and reusable

6. Single responsibility principle
Class should have only one reason to change
Because you can doesn’t mean you should

7. Open-close principle
System elements should be open for extension but closed
for modification
Lights can be dismantled without taking out an engine

8. Liskov substitution principle
Object of a derived class should be able to replace an object of the base class without
bringing any errors in the system or modifying the behavior of the base class
If it looks like a duck, and quack like a duck, but it needs batteries,
You probably have wrong level of abstraction

9. Interface segregation principle
Many specialized interfaces are better than one almighty.
A client should never be forced to implement an interface that it
doesn’t need or clients shouldn’t be forced to depend on methods
It’s not a good idea to mix electricity and water in one place

10. Dependency inversion principle
The high level module must not depend on the low level module.
Both modules should depend on abstractions.
Abstractions should not depend on details. Details should depend on
abstractions.
You don’t need to know how the engine is build to start it

11. KISS DRY YAGNI
YAGNI You Ain’t Gonna Need It

12. KISS DRY YAGNI
YAGNI DRY
Don’t Repeat
Yourself
WET
We Enjoy Typing
Write Everything Twice

13. KISS DRY YAGNI
YAGNI DRY KISS
Keep It Simple Stupid
Keep It Simple, Stupid
Keep it Simple Silly
Keep It Short & Simple
Keep It Small & Simple
Keep It Simple
&Straightforward

14. KISS DRY YAGNI
YAGNI DRY KISS