Static methods behavior in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a static method inside the class.

Python

class MyClass:
    @staticmethod
    def greet():
        print([1])

MyClass.greet()

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

Aself

Bcls

Cgreet

D"Hello from static method!"

Attempts:

3 left

💡 Hint

Common Mistakes

Using self or cls as parameters in static methods.

Trying to access instance variables inside static methods.

Static methods do not take self or cls as parameters. They behave like regular functions inside the class. Here, the method prints a string.

2fill in blank

medium

Complete the code to call the static method correctly from an instance.

Python

class Calculator:
    @staticmethod
    def add(a, b):
        return a + b

calc = Calculator()
result = calc.[1](5, 7)
print(result)

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

Aself

Badd

CCalculator

Dsum

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to call static method using class name without parentheses.

Using incorrect method names.

Static methods can be called from an instance using the method name. Here, calc.add(5, 7) calls the static method add.

3fill in blank

hard

Fix the error in the static method definition to make it work.

Python

class Utils:
    @staticmethod
    def multiply([1], b):
        return a * b

print(Utils.multiply(3, 4))

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

Aa

Bself

Ccls

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using self or cls as the first parameter in static methods.

Not defining parameters needed for the method.

Static methods do not receive self or cls automatically. You must define all parameters explicitly. Here, 'a' is the first parameter.

4fill in blank

hard

Fill both blanks to create a static method that returns the square of a number.

Python

class MathOps:
    @staticmethod
    def square([1]):
        return [2] * [1]

print(MathOps.square(6))

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

Anum

Cself

Dcls

Attempts:

3 left

💡 Hint

Common Mistakes

Using self or cls as parameters in static methods.

Using different variable names inside the method.

The static method takes one parameter 'num' and returns its square by multiplying it by itself.

5fill in blank

hard

Fill all three blanks to create a static method that filters and returns even numbers from a list.

Python

class Filter:
    @staticmethod
    def evens([1]):
        return [[2] for [3] in numbers if [2] % 2 == 0]

print(Filter.evens([1, 2, 3, 4, 5, 6]))

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

Anumbers

Bnum

Dself

Attempts:

3 left

💡 Hint

Common Mistakes

Using self as a parameter in static methods.

Using inconsistent variable names inside the list comprehension.

The static method takes a list 'numbers', iterates over it with 'num', and returns a list of even numbers.

Practice

1. What is a key characteristic of a staticmethod in Python?

easy

A. It does not receive the instance or class as the first argument.

B. It automatically receives the instance as the first argument.

C. It can only be called on an instance, not on the class.

D. It modifies the class state directly.

Solution

1. Step 1: Understand the role of static methods

   Static methods do not take the instance (self) or class (cls) as their first argument.

2. Step 2: Compare options with static method behavior

   It does not receive the instance or class as the first argument. correctly states this key feature, while others describe instance or class methods.

3. Final Answer:

   It does not receive the instance or class as the first argument. -> Option A

4. Quick Check:

   Static method = no self or cls [OK]

Hint: Static methods don't get self or cls automatically [OK]

Common Mistakes:

• Thinking static methods receive 'self' or 'cls'
• Confusing static methods with instance methods
• Believing static methods modify class state

2. Which of the following is the correct way to define a static method in a Python class?

easy

A. def method(self): pass

B. @classmethod\ndef method(cls): pass

C. @staticmethod\ndef method(): pass

D. def method(cls): pass

Solution

1. Step 1: Identify the decorator for static methods

   The @staticmethod decorator is used to define static methods.

2. Step 2: Check method signature

   Static methods do not take self or cls as parameters, so the method should have no parameters.

3. Final Answer:

   @staticmethod\ndef method(): pass -> Option C

4. Quick Check:

   @staticmethod + no self/cls = correct static method [OK]

Hint: Use @staticmethod decorator and no parameters [OK]

Common Mistakes:

• Forgetting @staticmethod decorator
• Including self or cls as parameters
• Confusing with @classmethod

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

class MyClass:
    @staticmethod
    def greet():
        return "Hello!"

print(MyClass.greet())

medium

A. TypeError: greet() missing 1 required positional argument

B. None

C. AttributeError: 'MyClass' object has no attribute 'greet'

D. "Hello!"

Solution

1. Step 1: Understand static method call

   Static methods can be called directly on the class without creating an instance.

2. Step 2: Check method return value

   The greet method returns the string "Hello!", so printing it outputs "Hello!".

3. Final Answer:

   "Hello!" -> Option D

4. Quick Check:

   Static method call returns "Hello!" [OK]

Hint: Call static methods on class directly to get return value [OK]

Common Mistakes:

• Expecting an instance to call static method
• Confusing static method with instance method needing self
• Misreading the output as an error

4. Identify the error in this code snippet:

class Example:
    @staticmethod
    def show(self):
        print("Static method")

Example.show()

medium

A. TypeError because static method has 'self' parameter

B. No error, prints "Static method"

C. SyntaxError due to decorator misuse

D. AttributeError: 'Example' has no attribute 'show'

Solution

1. Step 1: Check static method parameters

   Static methods should not have 'self' or 'cls' parameters because they are not passed automatically.

2. Step 2: Understand the call behavior

   Calling Example.show() passes no arguments, but method expects one ('self'), causing TypeError.

3. Final Answer:

   TypeError because static method has 'self' parameter -> Option A

4. Quick Check:

   Static method with 'self' causes TypeError [OK]

Hint: Static methods must not have self or cls parameters [OK]

Common Mistakes:

• Adding self parameter to static methods
• Assuming static methods get instance automatically
• Confusing static and instance methods

5. Given this class:

class Calculator:
    @staticmethod
    def add(a, b):
        return a + b

    @staticmethod
    def multiply(a, b):
        return a * b

# Which call is correct to get the product of 3 and 4?

hard

A. Calculator.multiply(self, 3, 4)

B. Calculator.multiply(3, 4)

C. Calculator.multiply()

D. Calculator.multiply(3)

Solution

1. Step 1: Understand static method parameters

   Static methods require all parameters to be passed explicitly since no self or cls is passed.

2. Step 2: Check each call for correctness

   Calculator.multiply(3, 4) correctly passes two arguments (3 and 4). Options B, C, and D have wrong or missing arguments.

3. Final Answer:

   Calculator.multiply(3, 4) -> Option B

4. Quick Check:

   Static method call with correct arguments works [OK]

Hint: Pass all arguments explicitly to static methods [OK]

Common Mistakes:

• Passing self to static methods
• Calling without required arguments
• Confusing static with instance method calls