SOLID: Design Principles

Posted on 05 Feb, 2021

1. Single Responsibility Principle

   • An object should do exactly one thing, and should be the only object in the codebase that does that one thing.
   • A class should have one, and only reason to change

2. Open-closed principle

   • A class should be open to extension, but closed to change.
   • You should be able to extend classes behaviour, without modifying it.

3. Liskov substitution principle

   • Derived classes must be substitutable for their base classes.
   • An extension of the Open Close Principle and it means that we must make sure that new derived classes are extending the base classes without changing their behavior.

4. Interface segregation principle

   • An interface should have as few methods as is feasible to provide the functionality of the role defined by the interface.
   • Make fine grained interfaces that are client specific.

5. Dependency Inversion principle

   • Depend on abstractions, not on concretions (concrete details)
   • High-level modules should not depend on low-level modules. Both should depend on abstractions (interfaces)
   • Abstractions should not depend on details. Details should depend on abstractions.

Resources

• Dependency Inversion Principle
• Liskov's Substitution Principle