Lecture 2: The Object-Oriented Model

Question 1

Model

Answer 1

An overview or representation of something. It overlooks all irrelevant details and focuses on the ones we are interested in.

Question 2

Object-oriented model

Answer 2

A way of making the model of a system so that each object in real life is represented by a corresponding object in the model. It focuses on the individual objects and their interactions.

Question 3

List 4 advantages of the OO model

Answer 3

• People tend to naturally think in terms of objects and their interactions, so it is easier to understand
• Easily map reality
• Easy to develop
• Easy to break down into smaller parts

Question 4

Properties of an object

Answer 4

• a unique identity
• state (attributes) –> represented by variables (fields)
• well-defined behaviour (operations) –> performed by functions (interface)

Question 5

Data encapsulation

Answer 5

Hiding the internal state and implementation of an object, and only allowing access through an interface.

Question 6

Advantages of data encapsulation

Answer 6

Simplification: the entire object can be taken as a whole without focusing on the internal details.
Provides barrier against direct changes