19.5. Encapsulation: Functions

19.5. Encapsulation: Functions

In programming, encapsulation is a fundamental principle that involves the idea of ​​combining data and methods into a single unit, namely a function. Encapsulation is one of the main features of Object Oriented Programming (OOP), but it is also an important concept in procedural programming. In this chapter, we'll explore encapsulation in the context of functions.

What is a function?

In general terms, a function is a block of code that performs a specific task. A function can take input data, known as parameters, process that data, and return a result. Functions are useful because they allow you to reuse code, making programs more efficient and easier to maintain.

Encapsulation in Functions

Function encapsulation is the process of grouping related code into a single logical unit, the function. This code bundling has two main benefits. First, it helps organize the code, making it easier to understand and maintain. Second, it allows code to be reused, reducing code duplication.

When a function is defined, it encapsulates a specific task. For example, a function can be created to average a list of numbers. This function can be called several times in different parts of the program, each time with a different list of numbers. Without the function, the code to calculate the average would have to be repeated each time this task needed to be performed.

How to create a function

Creating a function usually involves three steps: defining the function, calling the function, and returning a value.

Function Definition

A function definition begins with the keyword 'def', followed by the function name and parentheses. Inside the parentheses, you can list the parameters that the function should take. Next comes a colon and an indented block of code, which is the body of the function.

Function Call

Once a function is defined, it can be called by its name, followed by parentheses. Inside the parentheses, you must provide the arguments that correspond to the function's parameters. The function call executes the code in the function body.

Return a Value

A function can return a value using the 'return' keyword. When program execution reaches the 'return' statement, the function terminates and the value is returned to the point where the function was called.

Example of Encapsulation in Functions

Let's consider a simple example of encapsulation in functions. Suppose we have a program that needs to average three lists of numbers. Without functions, the code might look something like this:

list1 = [1, 2, 3, 4, 5]
sum1 = 0
for num in list1:
    sum1 += num
average1 = sum1 / len(list1)

list2 = [6, 7, 8, 9, 10]
sum2 = 0
for num in list2:
    sum2 += num
average2 = sum2 / len(list2)

list3 = [11, 12, 13, 14, 15]
sum3 = 0
for num in list3:
    sum3 += num
average3 = sum3 / len(list3)

With functions, we can wrap the code to calculate the average in a function and reuse it for each list:

def calculate_average(list):
    sum = 0
    for num in list:
        sum += num
    average = sum / len(list)
    return average

list1 = [1, 2, 3, 4, 5]
average1 = calculate_average(list1)

list2 = [6, 7, 8, 9, 10]
average2 = calculate_average(list2)

list3 = [11, 12, 13, 14, 15]
average3 = calculate_average(list3)

As you can see, encapsulating functions makes code more organized, easier to understand, and avoids code duplication.

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67Encapsulation: Arrays

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