Computer Science
Grade 9
20 min
Class Methods and Static Methods: Methods Related to the Class
Learn the difference between class methods and static methods and how to use them.
What you'll learn
- Identify and differentiate between class methods and static methods in Python code, explaining their purpose and use cases with 100% accuracy on a quiz.
- Apply class methods to correctly implement alternative constructors for a given class in Python, demonstrated by successfully creating at least two distinct constructors in a coding assignment, following all instructions.
- Solve problems by implementing static methods to create utility functions within a class that are independent of instance variables, as measured by successfully completing three out of four related coding challenge problems.
- Explain the advantages and disadvantages of using class methods and static methods compared to instance methods in Python, justifying their choice in specific scenarios with clear reasoning in a short answer response.
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Differentiate between instance methods, class methods, and static methods.
Correctly use the `@classmethod` decorator to create a method that operates on the class itself.
Correctly use the `@staticmethod` decorator to create a utility method within a class.
Explain the purpose of the `cls` parameter in a class method.
Identify scenarios where a class method is more appropriate than an instance method.
Create a class method that acts as an alternative constructor or factory.
Explain why static methods do not have access to class or instance state.
Imagine a `Game` class. How could the class itself keep track of the total number of players across ALL games, without asking a single game object? 🤔
In this lesson, we'll explore two special types of m...
2
Key Concepts & Vocabulary
TermDefinitionExample
Instance MethodA regular method that belongs to a specific object (an instance). It always takes `self` as its first argument, which refers to the object calling the method.In a `Dog` class, `my_dog.bark()` is an instance method. It uses `self` to know which specific dog is barking.
Class MethodA method that belongs to the class itself, not a specific object. It is marked with a `@classmethod` decorator and takes `cls` as its first argument, which refers to the class.A `Car` class might have a class method `Car.get_total_cars_made()` to return a count of all cars ever created from the `Car` blueprint.
Static MethodA method that is part of a class's namespace but doesn't operate on the instance or the class. It is marked with a `@staticmethod` decorator and...
3
Core Syntax & Patterns
Class Method Syntax
@classmethod
def method_name(cls, param1, param2):
# Code that uses 'cls'
Use this pattern when you need a method that works with the class itself. The `@classmethod` decorator is required, and the first parameter must be `cls` (by convention) to receive the class.
Static Method Syntax
@staticmethod
def method_name(param1, param2):
# Code that does not use 'cls' or 'self'
Use this pattern for utility functions that are related to the class but do not need to access any class or instance data. The `@staticmethod` decorator is required, and there is no special first parameter like `self` or `cls`.
4 more steps in this tutorial
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Sign Up Free to ContinueSample Practice Questions
Easy
Which decorator must be placed directly above a method definition to identify it as a class method?
A.@staticmethod
B.@classmethod
C.@instancemethod
D.@class
Easy
By convention, what is the name of the first parameter passed to a class method, which refers to the class itself?
A.self
B.object
C.cls
D.class
Easy
Which decorator must be placed directly above a method definition to identify it as a class method?
A.@staticmethod
B.@classmethod
C.@instancemethod
D.@class
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What grade level is "Class Methods and Static Methods: Methods Related to the Class"?
Class Methods and Static Methods: Methods Related to the Class is a Grade 9 Computer Science lesson on ExcelOS.
What will I learn in Class Methods and Static Methods: Methods Related to the Class?
You'll be able to: Identify and differentiate between class methods and static methods in Python code, explaining their purpose and use cases with 100% accuracy on a quiz; Apply class methods to correctly implement alternative constructors for a….
Is "Class Methods and Static Methods: Methods Related to the Class" free to practice?
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How many practice questions are included with Class Methods and Static Methods: Methods Related to the Class?
This lesson includes 25 practice questions across multiple difficulty levels, each with instant feedback and explanations.