Object-Oriented Design and SOLID Principles

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Questions and Answers

Which of the following is NOT a characteristic of the Open-Closed Principle (OCP)?

Software entities should be open for extension.
Single change results in cascade of changes. (correct)
Software entities should be closed for modification.
Modules never change once they are written.

In the context of object-oriented design, what primarily distinguishes composition from inheritance?

Composition involves combining objects or data types into more complex ones, while inheritance establishes a hierarchical relationship. (correct)
Composition allows for code reuse, while inheritance does not.
Composition represents an 'is-a' relationship, while inheritance represents a 'has-a' relationship.
Composition is applicable only in procedural-oriented design.

Which statement best describes the Interface Segregation Principle (ISP)?

Every class should implement all methods of an interface.
Large interfaces should be split into smaller, more specific interfaces so that clients only need to know about the methods they use. (correct)
Interfaces should be designed to be as general-purpose as possible.
Clients should be forced to depend on methods they do not use within an interface.

What is the primary goal of the Dependency Inversion Principle (DIP)?

To decouple software modules by having both high-level and low-level modules depend on abstractions. (D) Signup and view all the answers

Which design principle is most concerned with ensuring that a class has only one reason to change?

Single Responsibility Principle (SRP) (A) Signup and view all the answers

What is the key requirement emphasized by the Liskov Substitution Principle (LSP)?

Subtypes must be substitutable for their base types without altering the correctness of the program. (D) Signup and view all the answers

Consider a scenario where a class calculates both the area of a shape and logs the calculation. Which SOLID principle is being violated?

Single Responsibility Principle (SRP) (D) Signup and view all the answers

In object-oriented design, association differs primarily from aggregation in what aspect?

Association specifies how objects are related to each other, and aggregation indicates that one object has owner ship of another object with independent lifecycles (A) Signup and view all the answers

Given two classes, `A` and `B`, where class `B` aggregates class `A`, what does this imply about the lifecycle of objects of class `A`?

Objects of class <code>A</code> can exist independently of objects of class <code>B</code>. (C) Signup and view all the answers

What is the critical distinction between aggregation and composition in object-oriented design?

Aggregation implies a weaker relationship and lifecycle dependency than composition. (C) Signup and view all the answers

Which of the following scenarios best exemplifies a violation of the Liskov Substitution Principle?

A subclass throws an unexpected exception that the client can see when using a method of the base class where the client does not expect it. (D) Signup and view all the answers

In the context of SOLID principles, what does 'open for extension' primarily mean regarding software entities?

New functionality can be added without modifying existing code. (B) Signup and view all the answers

How does applying the Interface Segregation Principle contribute to code maintainability?

By reducing dependencies and the impact of changes, since clients only depend on necessary methods. (A) Signup and view all the answers

Dependency Inversion Principle (DIP) promotes which of the following architectural patterns?

Plug-in architecture where high-level modules define interfaces that they use and low-level modules provide concrete implementations of those. (C) Signup and view all the answers

Which of the following is NOT a goal of applying SOLID principles in software design?

Minimizing code reusability. (A) Signup and view all the answers

Which of the following is the best example of a scenario where composition would be more appropriate than inheritance?

Creating a <code>Car</code> class that needs an <code>Engine</code> with ability to swap out different <code>Engine</code> types at runtime. (B) Signup and view all the answers

What is the main disadvantage of violating the Open-Closed Principle?

Increased risk of introducing bugs when modifying existing code. (C) Signup and view all the answers

Consider a class `Rectangle` with methods to set `Width` and `Height`. If a `Square` class inherits from `Rectangle`, what potential problem arises regarding the Liskov Substitution Principle?

Setting either <code>Width</code> or <code>Height</code> in <code>Square</code> should also set the other, violating expected behavior of <code>Rectangle</code>. (D) Signup and view all the answers

Which of the following scenarios indicates the need to apply the Interface Segregation Principle?

A class only uses a small subset of methods from a large interface. (B) Signup and view all the answers

How can the Dependency Inversion Principle improve the testability of a software system?

By allowing the use of mock or stub implementations for dependencies during unit testing. (B) Signup and view all the answers

Which of these statements about object-oriented design is correct?

Aggregation is a special form of association. (B) Signup and view all the answers

A car consists of an engine, wheels, and a chassis. If the car is destroyed, the engine, wheels, and chassis cease to exist independently. What kind of relationship is this?

Composition (C) Signup and view all the answers

In the context of the Single Responsibility Principle, which of the following is the most accurate description of a 'responsibility'?

A reason for a class to change. (B) Signup and view all the answers

You have a logging module used across your application. You want to add the ability to log to a new type of data sink without modifying existing code. Which principle supports this?

Open/Closed Principle (B) Signup and view all the answers

Why is cohesion considered an important characteristic in software design?

It ensures the module contains tightly related functionalities, which reduces complexity, and increases understandability and maintainability (C) Signup and view all the answers

Flashcards

What is Association?

A relationship between objects. When objects are related to one another.

What is Aggregation in OO?

A special form of association where all objects have their own lifecycle but there is ownership.

What is Composition in OO?

A technique to combine objects or data types into more complex one.

Single Responsibility Principle (SRP)

States that every module, class, or function should have responsibility over a single part of functionality.