OOP

Question 1

objects

Answer 1

instances of a class

Question 2

class

Answer 2

objects characterised by the same attributes & behaviour

Question 3

3 special methods

Answer 3

1. __init__
2. __str__ & __repr
3. __len__

Question 4

__init__

Answer 4

constructor method

Question 5

__str__

Answer 5

• str() on an object
• more readable & user-friendly
• targeted for end-users

Question 6

__repr__

Answer 6

• repr() on an object
• more detailed
• used for debugging & logging
• targeted for developers

Question 7

what are the 2 types of instance relationships

Answer 7

1. association
2. comparision

Question 8

association relationship

Answer 8

for general relationship describing when one class uses the functionalities provided by another class

Question 9

composition relationship

Answer 9

for the relationship between a whole thing & its component parts

Question 10

why do we use inheritance

Answer 10

1. model an ‘is a kind of’ relationship
2. subclasses can add more fields & methods or make changes to existing methods in the parentclass to extend behaviour

Question 11

when should we not use inheritance

Answer 11

just as a way of sharing fields & methods between classes

Question 12

syntax for inheritance

Answer 12

class subClass(SuperClass)

Question 13

superclass vs subclass

Answer 13

• subclasses can override methods from superclass to provide specific functionality
• when a method with the same name were defined in both superclass & a subclass, use super() to refer to method in superclass
• using super to reuse initialisation and other superclass’ methods helps avoid repeating code across classes