Low Level Design 104 | How to build Classes in Object Oriented Design | 2022 | System Design | Summary and Q&A

TL;DR

Learn how to assign responsibilities to classes and understand class relations in object-oriented design.

Key Insights

• 🏛️ Class relationships can be "has a" (composition) or "is a" (inheritance).
• 🏛️ Responsibilities should be assigned to classes based on their functionality and interactions.
• 🎨 Encapsulation and abstraction are essential concepts in object-oriented design.
• 👨‍💻 The location of methods and responsibilities in classes impacts code organization and maintainability.
• 🦮 Solid principles guide the design of well-structured and flexible object-oriented systems.
• 👨‍💻 Class coupling and message passing should be minimized to improve code quality.
• 🎨 Polymorphism and inheritance are other important concepts in object-oriented design.

Transcript

hello and welcome to sudoku this is another video in lld series in this video we are going to talk about how do we assign different responsibilities to the classes that we have first designed in the class diagram in the previous video if you have not checked out the previous video please go check it out where we have taken a particular use case of ... Read More

Questions & Answers

Q: What are the two types of class relationships?

The two types of class relationships are "has a" (composition) and "is a" (inheritance).

Q: How can we represent a "has a" relationship in a class diagram?

A "has a" relationship is represented using a solid diamond arrow.

Q: Can a class have multiple "is a" relationships?

Yes, a class can have multiple "is a" relationships as it can inherit from multiple parent classes.

Q: How do we assign responsibilities to classes?

Responsibilities are assigned based on the functionality and interactions of classes. Each class should have methods that fulfill its specific responsibilities.

Q: Where should the calculation of discounts in a lesson class be placed?

The calculation of discounts can be placed in either the lesson class or the card class, depending on the system's design and requirements.

Q: Where should the checkout method be placed in a system?

The checkout method is ideally placed in the customer class to reduce coupling between classes and maintain encapsulation.

Q: What are the principles of solid object-oriented design?

The solid principles include Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion.

Q: How does encapsulation and abstraction contribute to object-oriented design?

Encapsulation and abstraction help in hiding information and reducing coupling between classes, resulting in more robust and maintainable code.

Q: What are the two types of class relationships?

The two types of class relationships are "has a" (composition) and "is a" (inheritance).

More Insights

• Class relationships can be "has a" (composition) or "is a" (inheritance).

• Responsibilities should be assigned to classes based on their functionality and interactions.

• Encapsulation and abstraction are essential concepts in object-oriented design.

• The location of methods and responsibilities in classes impacts code organization and maintainability.

• Solid principles guide the design of well-structured and flexible object-oriented systems.

• Class coupling and message passing should be minimized to improve code quality.

• Polymorphism and inheritance are other important concepts in object-oriented design.

• Object-oriented design principles aim to create modular, extensible, and reusable code.

Summary & Key Takeaways

• Classes in a system interact and depend on each other to fulfill use cases.

• Class relationships can be "has a" (composition) or "is a" (inheritance).

• Responsibilities are assigned to classes based on their functionality and interactions with other classes.