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Principles

Solid Principles🔗

  • Single Responsibility Principle (SRP) - Do one thing and do it well.
  • Open/Closed Principle - Don’t modify existing code; extend it instead.
  • Liskov Substitution Principle (LSP) - Derived classes must extend without changing functionality.
  • Interface Segregation Principle (ISP) - Many small interfaces are better than one large one.
  • Dependency Inversion Principle (DIP) - Depend on abstractions, not concretions.

General OOPs Principles🔗

  • Encapsulation - Hide implementation details; expose only what is necessary
  • Prefer Composition over Inheritance - Favor has-a over is-a relationship
  • Tell, Don't Ask - Ask for what you need, not how to get it

Code Simplicity & Maintainability Principles🔗

  • KISS (Keep it Simple, Stupid) - Complexity is the enemy of maintainability
  • YAGNI (You ain't gonna need it) - Avoid unnecessary features
  • DRY (Don't Repeat Yourself) - Every piece of knowledge must have a single representation.
  • Law of Demeter (LoD) - Talk only to your friends, not strangers.

Design and Architecture🔗

  • Separation of Concerns - Each module should have a clear purpose.
  • Cohesion & Coupling - Tightly coupled systems are harder to maintain. High Cohesion, Low Coupling.
  • Fail Fast - Crash early, fix early. Detect Early errors rather than failing silently
  • Convention over Configuration - Less configuration, more productivity. Use sensible Defaults.
  • Poka - Yoke (Mistake - Proofing) - Make incorrect states impossible
  • Single Level of Abstraction - Don’t mix high and low-level details in the same function.

Performance & Scalability Principles🔗

  • You shouldn't Optimize prematurely - Premature optimization is the root of all evil. Donald Knuth
  • C10k & C10M Problem Awareness - Plan for high concurrency. Be mindful of 10k+ concurrent connections in server
  • Horizontal Scaling vs Vertical Scaling - Scale out, not up. Prefer Horizontal Scaling.

Software Development Process Principles🔗

  • Agile Manifesto - Prioritize individuals, working software, customer collaboration, and flexibility. - Respond to change over following a plan.
  • Boy Scout Rule - Leave the code better than you found it. - Always leave the campground cleaner than you found it.
  • Test Driven Development (TDD) - Write tests first, then write the code to pass them. - Red → Green → Refactor.
  • CI/CD - Automate testing and deployment. - Deploy fast, deploy often.
  • Feature Flags/Toggle - Enable or disable features without deploying code. - Separate deployment from release.

Security & Reliability Principles🔗

  • Principle of Least Privilege - Don’t give a process more power than it needs.
  • Fail Safe, Not Open - Systems should default to a safe state in case of failure. - Security should not rely on obscurity.
  • Indepotency - The same request should produce the same result if repeated. - Safe to retry.”
  • CAP Theorem - In distributed systems, you can have only two out of three: * Consistency (all nodes see the same data) * Availability (system always responds) * Partition Tolerance (handles network failures)