Public attributes in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a public attribute named name in the Person class.

Python

class Person:
    def __init__(self, [1]):
        self.name = name

p = Person("Alice")
print(p.name)

Drag options to blanks, or click blank then click option'

Aage

Bself

Cname

Dperson

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'self' as a parameter name instead of 'name'.

Forgetting to pass the parameter when creating the object.

The __init__ method takes name as a parameter to set the public attribute self.name.

2fill in blank

medium

Complete the code to access the public attribute color of the Car object.

Python

class Car:
    def __init__(self, color):
        self.color = color

my_car = Car("red")
print(my_car.[1])

Drag options to blanks, or click blank then click option'

Amodel

Bspeed

Cowner

Dcolor

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to access an attribute that does not exist.

Using parentheses like a method call instead of attribute access.

To get the value of the public attribute color, use my_car.color.

3fill in blank

hard

Fix the error in the code by completing the blank to correctly set the public attribute age.

Python

class Animal:
    def __init__(self, age):
        self.[1] = age

cat = Animal(3)
print(cat.age)

Drag options to blanks, or click blank then click option'

Ayears

Bage

Cold

Dage_

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different attribute name than the one accessed.

Misspelling the attribute name.

The attribute name must match the one used when accessing it later, which is age.

4fill in blank

hard

Fill both blanks to create a public attribute height and print its value.

Python

class Tree:
    def __init__(self, [1]):
        self.[2] = height

pine = Tree(15)
print(pine.height)

Drag options to blanks, or click blank then click option'

Aheight

Bsize

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for parameter and attribute.

Using a name not matching the print statement.

The parameter and attribute names should both be height to correctly set and access the value.

5fill in blank

hard

Fill all three blanks to create a public attribute width, set it, and print it.

Python

class Box:
    def __init__(self, [1]):
        self.[2] = width

b = Box(10)
print(b.[3])

Drag options to blanks, or click blank then click option'

Awidth

Dheight

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for parameter, attribute, or access.

Using 'height' instead of 'width'.

All blanks should be width to correctly pass, set, and access the public attribute.

Practice

1. What is a public attribute in a Python class?

easy

A. An attribute that can be accessed and changed from outside the class

B. An attribute that is hidden and cannot be accessed outside the class

C. A method that runs automatically when an object is created

D. A special function to delete an object

Solution

1. Step 1: Understand attribute visibility

   Public attributes are designed to be accessed and modified from outside the class.

2. Step 2: Compare options

   An attribute that can be accessed and changed from outside the class correctly describes public attributes. Options A, B, and D describe other concepts.

3. Final Answer:

   An attribute that can be accessed and changed from outside the class -> Option A

4. Quick Check:

   Public attribute = accessible outside [OK]

Hint: Public means anyone can access or change it [OK]

Common Mistakes:

• Confusing public with private attributes
• Thinking methods are attributes
• Mixing up constructors with attributes

2. Which of the following is the correct way to create a public attribute name inside a Python class constructor?

easy

A. self->name = value

B. self.name = value

C. name = self.value

D. def name(self):

Solution

1. Step 1: Recall syntax for public attributes

   Inside __init__, public attributes are created by assigning to self.attribute_name.

2. Step 2: Check each option

   self.name = value uses correct syntax: self.name = value. Others are invalid Python syntax or wrong usage.

3. Final Answer:

   self.name = value -> Option B

4. Quick Check:

   Use self.attribute = value [OK]

Hint: Use self.attribute = value inside __init__ [OK]

Common Mistakes:

• Using def instead of assignment
• Wrong arrow syntax like self->name
• Assigning attribute to name instead of self.name

3. What will be the output of this code?

class Dog:
    def __init__(self, name):
        self.name = name

my_dog = Dog('Buddy')
print(my_dog.name)

medium

A. Dog

B. Error

C. my_dog

D. Buddy

Solution

1. Step 1: Understand attribute assignment

   The constructor sets self.name to the value passed, which is 'Buddy'.

2. Step 2: Print the attribute value

   Printing my_dog.name outputs 'Buddy'.

3. Final Answer:

   Buddy -> Option D

4. Quick Check:

   Print attribute value = Buddy [OK]

Hint: Print object.attribute to see stored value [OK]

Common Mistakes:

• Expecting class name instead of attribute value
• Confusing object name with attribute
• Thinking it causes an error

4. Find the error in this code that tries to create a public attribute age:

class Person:
    def __init__(self, age):
        age = age

p = Person(30)
print(p.age)

medium

A. The attribute should be assigned to self.age, not age

B. The print statement should be print(age)

C. The constructor is missing a return statement

D. The class name should be lowercase

Solution

1. Step 1: Check attribute assignment

   Assigning age = age only creates a local variable, not an attribute of the object.

2. Step 2: Correct attribute assignment

   It should be self.age = age to create a public attribute accessible outside.

3. Final Answer:

   The attribute should be assigned to self.age, not age -> Option A

4. Quick Check:

   Use self.attribute = value to create public attribute [OK]

Hint: Always assign attributes to self.attribute inside __init__ [OK]

Common Mistakes:

• Assigning to local variable instead of self.attribute
• Trying to print variable not attached to object
• Thinking constructor needs return

5. You want to create a class Car that stores the public attributes make and year. Which code correctly creates these attributes and allows access to them?

hard

A. class Car:
def __init__(self, make, year):
self.make = make
year = self.year

my_car = Car('Toyota', 2020)
print(my_car.make, my_car.year)

B. class Car:
def __init__(self, make, year):
make = self.make
year = self.year

my_car = Car('Toyota', 2020)
print(my_car.make, my_car.year)

C. class Car:
def __init__(self, make, year):
self.make = make
self.year = year

my_car = Car('Toyota', 2020)
print(my_car.make, my_car.year)

D. class Car:
def __init__(self, make, year):
self.make = make
self.year = year

my_car = Car('Toyota', 2020)
print(make, year)

Solution

1. Step 1: Check attribute assignments

   class Car: def __init__(self, make, year): self.make = make self.year = year my_car = Car('Toyota', 2020) print(my_car.make, my_car.year) correctly assigns self.make and self.year to the passed values.

2. Step 2: Check attribute access

   class Car: def __init__(self, make, year): self.make = make self.year = year my_car = Car('Toyota', 2020) print(my_car.make, my_car.year) prints my_car.make and my_car.year, which are valid public attributes.

3. Final Answer:

   class Car: def __init__(self, make, year): self.make = make self.year = year my_car = Car('Toyota', 2020) print(my_car.make, my_car.year) -> Option C

4. Quick Check:

   Assign and access via self.attribute and object.attribute [OK]

Hint: Assign attributes to self and access via object.attribute [OK]

Common Mistakes:

• Assigning attributes backwards (make = self.make)
• Accessing attributes without object prefix
• Mixing local variables with attributes