Python Class & Static Methods Flashcards

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Questions and Answers

What are class methods?

Lesson 78

What is a class method?

They are called by a class, which is passed to the cls parameter of the method.

What does the following code output? `square = Rectangle.new_square(5); print(square.calculate_area())`

What is `new_square`?

new_square is a class method that returns a new object of the class. Signup and view all the answers

Complete the function definition to make `sayHi()` a class method.

@classmethod def sayHi(cls): print("Hi") Signup and view all the answers

What are static methods?

They are similar to class methods except they don't receive any additional arguments. Signup and view all the answers

What does the `validate_topping` static method in the Pizza class do?

It raises a ValueError if 'pineapple' is passed. Signup and view all the answers

Which of these is most likely to be a static method?

def spam(x, y): (C) Signup and view all the answers

What are properties in Python?

Lesson 79 Signup and view all the answers

How are properties created?

By putting the property decorator above a method. Signup and view all the answers

What is the output of: `pizza.pineapple_allowed = True`

AttributeError: can't set attribute Signup and view all the answers

Complete the `isAdult` property.

if self.age > 18: return True else: return False Signup and view all the answers

What is the purpose of the property decorator?

To define a method as a property of a class. Signup and view all the answers

What does this code do: `@pineapple_allowed.setter`?

Defines a setter for the pineapple_allowed property. Signup and view all the answers

What is the purpose of the split method on a string?

Divides the input into separate words. Signup and view all the answers

Why does Goblin inherit from GameObject?

Goblin is a kind of GameObject. Signup and view all the answers

Why was desc turned into a property?

So it could be dynamically created when accessed. Signup and view all the answers

What do you need to create a property?

Using the property decorator. Signup and view all the answers

What differentiates a class method from a static method?

Class methods are passed the calling class, static methods aren't. Signup and view all the answers

What are the usual parameter names for the calling instance and class?

self and cls. Signup and view all the answers

What method is called just before an object is instantiated?

init Signup and view all the answers

Fill in the blanks to access `egg` attribute strongly private.

_ _egg = 7 Signup and view all the answers

What is garbage collection?

Garbage collection. Signup and view all the answers

Fill in the blanks to make a setter for the name property.

@name.setter def name(self, value): self._name = value Signup and view all the answers

Complete the `add` method for the Juice class.

return Juice(self.name +'&' +other.name, self.capacity + other.capacity) Signup and view all the answers

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Study Notes

Class Methods

Class methods are invoked by the class itself, receiving the class as the first parameter named cls.
They allow the creation of instances without requiring an explicit instance of the class.
Example: In the Rectangle class, new_square is a class method that creates a square instance via cls.

Static Methods

Static methods belong to a class but do not take any instance or class as an argument.
Functionality is similar to regular functions within a class context.
Example: In the Pizza class, validate_topping verifies topping compliance without using class or instance parameters.

Properties in Python

Properties are defined using the @property decorator that allows controlled access to instance attributes.
They can provide getter and setter capabilities for encapsulation and validation, maintaining class integrity.
Example: In the Pizza class, pineapple_allowed is defined as a property that restricts direct modification.

Game Logic and Object Inheritance

The Goblin class is derived from GameObject, demonstrating Object-Oriented Programming (OOP) principles of inheritance, hinting that Goblin exhibits characteristics of a GameObject.
Properties can be made dynamic, such as when attributes are computed or restricted at access time.

Property Creation and Decorators

Properties are created using the @property decorator, while setters are defined with @property_name.setter.
Example of setter creation for name property in the Person class modifies how attributes can be handled when set.

Memory Management

The process of automatic memory cleanup in Python is referred to as Garbage Collection, ensuring efficient memory use by removing unreferenced objects.

Operator Overloading

The __add__ method allows customizing behavior when using the + operator between instances of custom classes.
In the Juice class example, combining two juice instances results in a new instance with combined names and capacities.

Summary of Class & Static Methods Differences

Class methods receive the class (cls), while static methods do not receive either an instance or class data — they operate independently.
Class methods are bound to the class and can manipulate class state, whereas static methods are utility functions within the class itself.

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