SOLID Principles

SOLID Principles

SOLID principles are a set of five design principles in object-oriented programming—Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion. They aim to make software more modular, maintainable, and scalable. 

1. Single Responsibility Principle (SRP):

The Single Responsibility Principle (SRP) states that a class should have only one reason to change, meaning it should have only one responsibility

   - When to use: Use when a class should have only one reason to change, i.e., it should have only one responsibility.

   - Why: It enhances maintainability by isolating changes to a single responsibility.

   - Where: Apply to classes, methods, or modules.

2. Open/Closed Principle (OCP):

  The Open/Closed Principle (OCP) states that a class should be open for extension but closed for modification. This means that the behavior of a class can be extended without modifying its source code

 - When to use: Use when you want a class to be open for extension but closed for modification.

   - Why: Promotes code stability by allowing new functionality through extensions, without altering existing code.

   - Where: Apply when designing frameworks or base classes.

3. Liskov Substitution Principle (LSP):

   The Liskov Substitution Principle (LSP) states that objects of a superclass should be able to be replaced with objects of a subclass without affecting the correctness of the program. In other words, if a class S is a subclass of class T, an object of type T should be replaceable with an object of type S without affecting the functionality of the program.

- When to use: Use when inheriting from a base class or implementing an interface.

   - Why: Ensures that objects of a derived class can replace objects of the base class without affecting program correctness.

   - Where: Apply to inheritance relationships.

4. Interface Segregation Principle (ISP):

   The Interface Segregation Principle (ISP) states that a class should not be forced to implement interfaces it does not use. In other words, it suggests that a class should not be burdened with methods it does not need

- When to use: Use when a class should not be forced to implement interfaces it does not use.

   - Why: Prevents the problem of large, monolithic interfaces and promotes more specific, client-specific interfaces.

   - Where: Apply to interfaces and classes implementing them.

5. Dependency Inversion Principle (DIP):

   The Dependency Inversion Principle (DIP) states that high-level modules (e.g., business logic) should not depend on low-level modules (e.g., data access or specific implementations); both should depend on abstractions (e.g., interfaces or abstract classes). Additionally, abstractions should not depend on details; details should depend on abstractions. This principle helps to decouple components and make the system more flexible and maintainable.

- When to use: Use when high-level modules should not depend on low-level modules but both should depend on abstractions.

   - Why: Inverts the conventional dependency flow, reducing coupling and making the system more flexible and maintainable.

   - Where: Apply in the design of overall system architecture.

These principles collectively contribute to building robust, flexible, and maintainable software. The decision to apply them depends on the specific context and requirements of your software project.