Getter and setter methods in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a getter method for the attribute 'name'.

Python

class Person:
    def __init__(self, name):
        self._name = name

    def get_name(self):
        return self.[1]

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

A_name

Bname

Cself._name

Dself.name

Attempts:

3 left

💡 Hint

Common Mistakes

Returning 'name' instead of '_name'.

Including 'self' again inside the return statement.

The getter method returns the private attribute _name using self._name. Since self. is already in the code, you need to write _name after it, so the full expression is self._name.

2fill in blank

medium

Complete the code to define a setter method for the attribute 'age'.

Python

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

    def set_age(self, age):
        self.[1] = age

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

Aself._age

Bself.age

Cage

D_age

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning to 'age' instead of '_age'.

Writing 'self.self._age' by mistake.

The setter method assigns the new value to the private attribute _age. Since self. is already in the code, you need to write _age after it, so the full expression is self._age.

3fill in blank

hard

Fix the error in the setter method to correctly update the private attribute '_salary'.

Python

class Employee:
    def __init__(self, salary):
        self._salary = salary

    def set_salary(self, salary):
        [1] = salary

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

Aself._salary

B_salary

Csalary

Dself.salary

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning to '_salary' without 'self.', which does not update the attribute.

Assigning to 'salary' which is just the parameter.

The setter method must assign the new value to self._salary. Without self., the assignment only creates a local variable and does not update the attribute.

4fill in blank

hard

Fill both blanks to create a property for 'height' with getter and setter methods.

Python

class Person:
    def __init__(self, height):
        self._height = height

    @property
    def height(self):
        return self.[1]

    @height.setter
    def height(self, value):
        self.[2] = value

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

A_height

Bheight

Dheight_value

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'height' instead of '_height' in getter or setter.

Using different names in getter and setter.

The getter returns the private attribute _height. The setter assigns the new value to the same private attribute _height. Both blanks should be filled with _height.

5fill in blank

hard

Fill all three blanks to create a property 'weight' with getter, setter, and a condition to allow only positive values.

Python

class Person:
    def __init__(self, weight):
        self._weight = weight

    @property
    def weight(self):
        return self.[1]

    @weight.setter
    def weight(self, value):
        if value [2] 0:
            self.[3] = value

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

A_weight

B>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in the condition.

Assigning to 'weight' instead of '_weight'.

The getter returns self._weight. The setter checks if the new value is greater than zero, then assigns it to self._weight. So blanks are _weight, >, and _weight.

Practice

1. What is the main purpose of getter and setter methods in a Python class?

easy

A. To create new classes dynamically

B. To control access to private attributes safely

C. To execute code asynchronously

D. To delete objects from memory

Solution

1. Step 1: Understand getter and setter roles

   Getter methods retrieve attribute values, and setter methods update them while controlling access.

2. Step 2: Identify their purpose in encapsulation

   They protect private data by allowing controlled reading and writing, preventing direct access.

3. Final Answer:

   To control access to private attributes safely -> Option B

4. Quick Check:

   Getter/setter = control private data [OK]

Hint: Getters and setters manage private data access [OK]

Common Mistakes:

• Thinking they create new classes
• Confusing with asynchronous code
• Assuming they delete objects

2. Which of the following is the correct syntax to define a setter method for attribute age using the @property decorator in Python?

easy

A. @property.setter\ndef set_age(self, value):\n self._age = value

B. @setter.age\ndef age(self, value):\n self._age = value

C. @age.setter\ndef age(self, value):\n self._age = value

D. @age.setter\ndef set_age(self):\n self._age = value

Solution

1. Step 1: Recall setter syntax with @property

   The setter uses @attribute.setter decorator and method name matches the attribute.

2. Step 2: Check method signature

   Setter method takes self and value parameters to set the attribute.

3. Final Answer:

   @age.setter\ndef age(self, value):\n self._age = value -> Option C

4. Quick Check:

   Setter uses @age.setter and method age(self, value) [OK]

Hint: Setter uses @attribute.setter and method named attribute [OK]

Common Mistakes:

• Using wrong decorator like @setter.age
• Method name not matching attribute
• Setter missing value parameter

3. What will be the output of the following code?

class Person:
    def __init__(self, name):
        self._name = name

    @property
    def name(self):
        return self._name

    @name.setter
    def name(self, value):
        self._name = value.upper()

p = Person('alice')
p.name = 'bob'
print(p.name)

medium

A. bob

B. Error

C. alice

D. BOB

Solution

1. Step 1: Understand setter behavior

   Setter converts the assigned value to uppercase before storing it.

2. Step 2: Trace code execution

   Initially name is 'alice', then set to 'bob' which setter changes to 'BOB'. Printing returns 'BOB'.

3. Final Answer:

   BOB -> Option D

4. Quick Check:

   Setter uppercases value, output = BOB [OK]

Hint: Setter modifies value before storing, output reflects change [OK]

Common Mistakes:

• Expecting original lowercase 'bob'
• Thinking print shows initial 'alice'
• Assuming code raises error

4. Identify the error in this code snippet using getter and setter methods:

class Car:
    def __init__(self):
        self._speed = 0

    @property
    def speed(self):
        return self._speed

    @speed.setter
    def speed(self):
        self._speed = 100

c = Car()
c.speed = 50
print(c.speed)

medium

A. Setter method missing value parameter

B. Getter method missing return statement

C. Property decorator used incorrectly

D. No error, code runs fine

Solution

1. Step 1: Check setter method signature

   Setter must accept two parameters: self and value to set the attribute.

2. Step 2: Identify missing parameter

   Current setter only has self, missing value parameter, causing error on assignment.

3. Final Answer:

   Setter method missing value parameter -> Option A

4. Quick Check:

   Setter needs (self, value) parameters [OK]

Hint: Setter must have value parameter besides self [OK]

Common Mistakes:

• Omitting value parameter in setter
• Confusing getter and setter decorators
• Assuming code runs without error

5. You want to create a class Temperature that stores temperature in Celsius internally but allows getting and setting the temperature in Fahrenheit using getter and setter methods. Which code correctly implements this behavior?

hard

A. class Temperature:
def __init__(self, celsius=0):
self._celsius = celsius

@property
def fahrenheit(self):
return (self._celsius * 9/5) + 32

@fahrenheit.setter
def fahrenheit(self, value):
self._celsius = (value - 32) * 5/9

B. class Temperature:
def __init__(self, fahrenheit=32):
self._fahrenheit = fahrenheit

@property
def celsius(self):
return (self._fahrenheit - 32) * 5/9

@celsius.setter
def celsius(self, value):
self._fahrenheit = (value * 9/5) + 32

C. class Temperature:
def __init__(self, celsius=0):
self.celsius = celsius

@property
def fahrenheit(self):
return (self.celsius * 9/5) + 32

@fahrenheit.setter
def fahrenheit(self, value):
self.celsius = (value - 32) * 5/9

D. class Temperature:
def __init__(self, fahrenheit=32):
self.fahrenheit = fahrenheit

@property
def celsius(self):
return (self.fahrenheit - 32) * 5/9

@celsius.setter
def celsius(self, value):
self.fahrenheit = (value * 9/5) + 32

Solution

1. Step 1: Understand internal storage and interface

   The class stores temperature internally in Celsius (_celsius) but exposes Fahrenheit via getter and setter.

2. Step 2: Check getter and setter calculations

   Getter converts Celsius to Fahrenheit; setter converts Fahrenheit to Celsius and stores it.

3. Step 3: Verify correct use of private attribute and decorators

   class Temperature: def __init__(self, celsius=0): self._celsius = celsius @property def fahrenheit(self): return (self._celsius * 9/5) + 32 @fahrenheit.setter def fahrenheit(self, value): self._celsius = (value - 32) * 5/9 uses _celsius internally and @property/@fahrenheit.setter correctly.

4. Final Answer:

   Option A code correctly implements the behavior -> Option A

5. Quick Check:

   Internal Celsius, getter/setter convert Fahrenheit [OK]

Hint: Store Celsius internally, convert in getter/setter for Fahrenheit [OK]

Common Mistakes:

• Storing Fahrenheit internally instead of Celsius
• Using public attributes without underscore
• Mixing getter/setter names and attributes