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Now, let's relate this to programming:

Starter activity

Treasure Chest: This is like a class in programming.

Locked Chest: The class is "locked" in the sense that its internal workings are hidden from the outside world.

Key: Methods (functions) are like the key. They allow controlled access to the data inside the class.

Valuable Items: These are the attributes (data) inside the class.

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Now, let's relate this to programming:

Starter activity

This code simulates a locked treasure chest containing valuable items. We try to open the chest with a key, and if successful, we can access the items inside. Encapsulation ensures that only specific methods can interact with the chest and its contents, keeping them secure.

Explain how this code works

What will this code output?

Explanation:
Creating Classes:

We start by defining two classes: TreasureChest and ValuableItems.
The TreasureChest class represents a locked chest where valuable items are stored.
The ValuableItems class represents the valuable items inside the chest, like gold coins and precious gems.

Initializing Classes:

Each class has an __init__ method, which is called when we create a new instance of the class.
In the __init__ method, we initialize the attributes of the classes.
Attributes starting with __ are private, meaning they can only be accessed from within the class.

Opening the Chest:

The open_chest() method in the TreasureChest class is used to open the chest.
It takes a key as input and checks if it matches the correct key ("secret_key").
If the key is correct, the chest is unlocked (__locked becomes False), and a message is printed.
If the key is incorrect, a message indicating that the chest remains locked is printed.

Checking if the Chest is Open:

The is_open() method in the TreasureChest class is used to check if the chest is open.
It returns True if the chest is open (i.e., __locked is False), and False otherwise.

Accessing Valuable Items:

We create instances of the TreasureChest and ValuableItems classes (chest and items, respectively).
We attempt to open the chest with the wrong key first and check if it's open.
Then, we try to open the chest with the correct key and check its status again.
Finally, we access and print the number of gold coins and the list of precious gems inside the chest.

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Lesson 8: Encapsulation

Objectives

Lesson objectives:

Explore a program written using OOP
Explain the key concepts of OOP
Understanding of the terminology associated with OOP (including objects, properties/ attributes, methods, classes, inheritance, polymorphism, containment (aggregation), encapsulation, getters, setters, instances)

Literacy – Key Words
Instance	an occurrence of an object // a specific object based on the class // an instantiation of a class.
Inheritance	the capability of defining a new class of objects that has all the attributes and methods from a parent class.
Containment	a relationship in which one class has a component that is of another class type
Encapsulation	combining data and subroutines into a class and restricting external access to the data

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Now, let's relate this to programming:

Starter activity

Private Attributes:

In both the TreasureChest and ValuableItems classes, attributes are prefixed with double underscores (__), making them private.

These private attributes cannot be accessed directly from outside the class.

Getter Methods:

Both classes have methods (get_gold_coins() and get_precious_gems()) that allow indirect access to the private attributes.

These methods encapsulate access to the private attributes and provide controlled access from outside the class.

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Now, let's relate this to programming:

Starter activity

Setter Method:

Although not explicitly shown in the provided code, encapsulation could also involve setter methods to modify the private attributes, ensuring data integrity and validation.

Example (hypothetical setter method):

This setter method would encapsulate the modification of the __gold_coins attribute, allowing validation before changing its value.

Overall, encapsulation in this program ensures that the internal state of the TreasureChest and ValuableItems classes is protected and can only be accessed and modified through controlled interfaces (getter and setter methods), promoting data integrity and code maintainability.

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Knowledge Check

What is encapsulation in Python?

A) The process of breaking down a problem into smaller subproblems

B) The bundling of data and methods into a single unit

C) The process of converting code from one programming language to another

D) The process of optimizing code for better performance

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Question 1: Easy

Which of the following best describes containment in Python?

A) One class inherits from another class

B) One class contains an instance of another class

C) One class has access to methods of another class

D) One class overrides methods of another class

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Question 2: Easy

Which of the following is true about encapsulation?

A) It allows any part of the program to access and modify data freely�B) It hides the internal details of a class from the outside world�C) It only allows methods to be encapsulated, not data�D) It is only used in procedural programming, not in object-oriented programming

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Question 3: Medium

What is the purpose of encapsulation in Python?

A) To make code run faster�B) To make code easier to write�C) To hide the internal details of a class and protect its data�D) To enforce strict typing in Python

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Question 4: Medium

In Python, what prefix is commonly used to indicate a private attribute or method?

A) Single underscore ()�B) Double underscore ()�C) Triple underscore ()�D) No prefix is used

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Question 4: Difficult

Which of the following statements about encapsulation is false?

A) Encapsulation allows for data hiding and abstraction�B) Private attributes and methods can be accessed from outside the class�C) Encapsulation helps in maintaining code integrity and security�D) Encapsulation promotes modularity and code reusability

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Question 5: Difficult

Which access modifier in Python allows access to attributes and methods only within the class and its subclasses?

A) Public�B) Private�C) Protected�D) Hidden

In Python, access modifiers are used to control the accessibility of attributes and methods within a class. Here's a breakdown of each access modifier mentioned in the question:
Public: Public attributes and methods are accessible from anywhere, both within the class and outside of it. They have no restrictions on access. In Python, attributes and methods without any access modifier are considered public by default.
Private: Private attributes and methods are accessible only from within the class itself. They cannot be accessed directly from outside the class, not even from its subclasses. In Python, private attributes and methods are indicated by prefixing them with double underscores (e.g., __attribute, __method).
Protected: Protected attributes and methods are accessible within the class itself and its subclasses. They are not accessible from outside the class hierarchy. In Python, protected attributes and methods are indicated by prefixing them with a single underscore (e.g., _attribute, _method), although this is more of a convention than a strict enforcement.
Hidden: There's no access modifier called "Hidden" in Python. It's likely a distractor in the question.
So, the correct answer is C) Protected because it allows access to attributes and methods only within the class and its subclasses, which is the behavior desired in many object-oriented programming scenarios where you want to restrict access to certain parts of the class hierarchy while allowing access within it.

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Task 1: Understanding encapsulation

Activity 1

Create a Python class called Person with a private attribute __name. Implement a method get_name() to retrieve the name of the person.

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Task 2: Implementing encapsulation

Activity 2

Create a Python class called BankAccount with a private attribute __balance. Implement methods get_balance() to retrieve the balance and deposit(amount) to add funds to the account. Ensure that the balance cannot be accessed directly from outside the class.

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