Questions
22 of 24
1What are the SOLID principles? Explain each briefly.
2Explain the Single Responsibility Principle (SRP) with an example.
3Explain the Open/Closed Principle (OCP). How do you achieve it without modifying existing code?
4Explain the Liskov Substitution Principle (LSP). What happens if it's violated? (Square/Rectangle problem)
5Explain the Interface Segregation Principle (ISP). Why are fat interfaces bad?
6Explain the Dependency Inversion Principle (DIP). How does it relate to Dependency Injection?
7What is the difference between Aggregation and Composition?
8What is the Factory Pattern? How does it help in achieving OCP?
9What is the Abstract Factory Pattern? How does it differ from Factory Method?
10What is the Strategy Pattern? How does it replace complex conditional logic?
11What is the Observer Pattern? Where is it used in real life? (Event handling, Pub/Sub)
12What is the Decorator Pattern? How does it add functionality dynamically?
13What is a Singleton Pattern? What are the thread-safety concerns and how to handle them?
14What is an Anti-Pattern? Can you name a few? (God Object, Spaghetti Code, Golden Hammer)
15What is "Coupling" and "Cohesion"? Explain the relationship between them.
16What are Generics/Templates? How do they improve type safety and performance compared to casting?
17What is Type Erasure (Java) vs Reified Generics (C#)?
18What is Variance in Generics? (Covariance and Contravariance)
19What are Extension Methods (C#) or Default Methods (Java)? When should you use them?
20What is Reflection? How can it be used to break Encapsulation? What are the performance costs?
21What is the "Law of Demeter"? (Don't talk to strangers)
22Explain "Tell, Don't Ask" principle.
23What is the DRY principle? How does OOP help achieve it?
24What is the YAGNI principle?
OOPSOOPS
Basics
Inheritance and Composition
Polymorphism
Interfaces and Abstract Classes
Access Modifiers and Scope
Advanced Concepts and Design Principles
Trees
Real-World Design and Architecture Scenarios
22 / 24

Explain "Tell, Don't Ask" principle.

Difficulty: 4/10

Tell, Don't Ask

Tell, Don't Ask means that instead of retrieving an object's internal state and making decisions externally, we should tell the object to perform the operation that owns that decision. This keeps behavior close to the data and strengthens encapsulation. It is especially useful when external code contains conditionals based on another object's internal state. The principle does not mean getters are always wrong; querying is appropriate when the caller genuinely needs information.

javascript
  1. 1

    Keep business decisions near the state they govern.

  2. 2

    Reduce duplicated business rules in callers.

  3. 3

    Strengthens encapsulation.

  4. 4

    Can reduce coupling to object internals.

  5. 5

    Getters are not inherently bad; use them when exposing information is part of the abstraction.

Follow-up Questions

  • Is using getters always a violation?
  • How does Tell, Don't Ask relate to encapsulation?
  • How is it related to Law of Demeter?
  • Can Tell, Don't Ask produce overly large domain objects?
Share

Share via WhatsApp, X, Facebook, LinkedIn or copy link. Open Graph preview enabled.