Modules and Functions

In this chapter,​ we will talk about modules and functions.

We'll cover the following

Modules

A function is a block of code that is used to perform a single action. A module is a Python file containing a set of functions and variables of all types (arrays, dictionaries, objects, etc.) that you want to use in your application.

Module Creation

To create a module, create a python file with a .py extension.

Use a Module

Modules created with a .py extension can be used with an import statement.

Start up your Python REPL, and let’s use the “math” module that provides access to mathematical functions:

import math
print(math.cos(0.0))
print(math.radians(275))

Now, ​let’s create a module with a function and use the import statement to call the function:

main.py
module.py
def myCourse(name):
  print ("Course: " + name)

Functions

A function is a block of code that contains a sequence of instructions that are executed when the function is invoked. Data passed in the functions are known as function parameters.

Non-Parameterized Function

A function that does not contain parameters is a non-parameterized function.

The following defines the “do_hello” function that prints two messages when invoked:

def do_hello():
  print("Hello")
  print("World")
do_hello()

Note: Make sure that you insert a tab before both print expressions in the previous function. Tabs and spaces in Python are relevant and define that a block of code is somewhat dependent on a previous instruction. For instance, the print expressions are “inside” the “do_hello” function and, therefore, must have a tab.

Parameterized function

Functions that can receive parameters are parameterized functions.

The following Python code uses an “add_one()” function that receives a parameter ‘val’,and it prints the incremented value inside the function:

def add_one(val):
  print("Function got value",val+1)
  return
add_one(1)

Parameterized function with a return statement

Functions can also receive parameters and return values (using the “return” keyword).

The following Python code uses an “add_one()” function that receives a parameter ‘val’; it prints the value passed in the function, and returns the incremented value:

def add_one(val):
  print("Function got value", val)
  return val + 1
value = add_one(1)
print(value)

Now that the concept of ​modules and functions in python is clear, let’s check your knowledge in the upcoming exercises before moving on to the ‘Recursion’ lesson.