DRY and SOLID clean code principles

DRY

Don't Repeat Yourself. Instead of duplicating code, move it into a function/class to be reused and easily maintained.

From: The Pragmatic Programmer by Andy Hunt and Dave Thomas

SOLID

• Single responsibility: A class/module/function should have only one purpose.
• Open-closed: A class/module/function should e open for extension but closed for modification.
• Liskov substitution: Substituting a superclass with a subclass should not break the program.
• Interface segregation: Don't add methods to an interface that isn't needed by all classes that will implement it.
• Dependency inversion: high-level modules should depend only on abstractions (interfaces etc.). Low-level changes shouldn't affect high-level modules.

From: Robert C. Martin