Lecture 9

[フレーム]

Browse Course Material

Course Info

Instructors

Departments

Electrical Engineering and Computer Science

As Taught In

Fall 2016

Level

Undergraduate

Topics

Engineering
- Computer Science
  - Algorithms and Data Structures
  - Programming Languages

Learning Resource Types

Problem Sets

Lecture Notes

Lecture Videos

Programming Assignments with Examples

Download Course

In-Class Questions and Video Solutions

Getters and Setters

Which of the below is a getter method for the number of wheels?

----------------------------------
----------- Given ------------
----------------------------------
class Car(object):
 def __init__(self, w, d):
 self.wheels = w
 self.doors = d
 self.color = ""
----------------------------------
(A) def get_wheels():
 return wheels
(B) def get_wheels():
 return self.wheels
(C) def get_wheels(self):
 return wheels
(D) def get_wheels(self):
 return self.wheels

def get_wheels():
 return wheels

def get_wheels():
 return self.wheels

def get_wheels(self):
 return wheels

def get_wheels(self):
 return self.wheels

check

Subclass

What line could replace ____blank____ to create a class that inherits from Animal in the code below?
```
____blank____
 def speak(self):
 print("ruff ruff")
(line1) d = Dog(7)
(line2) d.set_name("Ruffles")
(line3) d.speak()
```
class Dog(Animal): check

class Animal(Dog): close

class Dog(object) close

With this definition of Dog, you run a program with line1, line2, and line3 above. What happens? Refer to the lecture slides for the code making up the “Animal” class.
Error on (line1) because Dog does not have an __init__ close

Uses the __init__ from Animal, but then an error (line2) because Dog does not have a set_name method. close

Uses the __init__ and set_name from Animal, but then an error (line3) because all methods must return something. close

Runs, creates a Dog object with age=7 and name=“Ruffles”, and prints “ruff ruff” check