{"id":96,"date":"2020-10-03T01:32:14","date_gmt":"2020-10-03T01:32:14","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=96"},"modified":"2025-03-30T09:56:51","modified_gmt":"2025-03-30T09:56:51","slug":"python-module","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-basics\/python-module\/","title":{"rendered":"Python Modules"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about Python modules, how to import objects from a module, and how to develop your modules.<\/p>\n\n\n\n

Introduction to Python modules #<\/a><\/h2>\n\n\n\n

A module is a piece of software that has a specific functionality. A Python module is a file that contains Python code.<\/p>\n\n\n\n

For example, when building a shopping cart application, you can have one module for calculating prices and another module for managing items in the cart. Each module is a separate Python source code file.<\/p>\n\n\n\n

A module has a name specified by the filename without the .py<\/code> extension. For example, if you have a file called pricing.py<\/code>, the module name is pricing<\/code>.<\/p>\n\n\n\n

Writing Python modules #<\/a><\/h2>\n\n\n\n

First, create a new file called pricing.py<\/code> and add the following code:<\/p>\n\n\n

# pricing.py<\/span>\n\ndef<\/span> get_net_price<\/span>(price, tax_rate, discount=0<\/span>)<\/span>:<\/span>\n    discounted_price = price * (1<\/span> - discount) \n    net_price = discounted_price * (1<\/span> + tax_rate) \n    return<\/span> net_price\n\n\ndef<\/span> get_tax<\/span>(price, tax_rate=0<\/span>)<\/span>:<\/span>\n    return<\/span> price * tax_rate<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The pricing module has two functions that calculate the net price and tax from the selling price, tax rate, and discount.<\/p>\n\n\n\n
Importing module objects #<\/a><\/h2>\n\n\n\n
To use objects defined in a module from another file, you can use the import<\/code> statement. <\/p>\n\n\n\n
The import<\/code> statement has several forms that we will discuss in the next sections.<\/p>\n\n\n\n
import <module_name> #<\/a><\/h3>\n\n\n\n
To use objects defined in a module, you need to import the module using the following import<\/code> statement:<\/p>\n\n\n
import<\/span> module_name<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
For example, to use the pricing<\/code> module in the main.py<\/code> file, you use the following statement:<\/p>\n\n\n
import<\/span> pricing<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
When you import a module, Python executes all the code from the corresponding file. In this example, Python executes the code from the pricing.py<\/code> file. Also, Python adds the module name to the current module. <\/p>\n\n\n\n
module_name.function_name()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The following shows how to use the get_net_price()<\/code> function defined in the pricing<\/code> module in the main.py<\/code> file:<\/p>\n\n\n
# main.py<\/span>\nimport<\/span> pricing\n\n\nnet_price = pricing.get_net_price(\n    price=100<\/span>,\n    tax_rate=0.01<\/span>\n)\n\nprint(net_price)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
101.0<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
import <module_name> as new_name #<\/a><\/h3>\n\n\n\n
If you don’t want to use the pricing<\/code> as the identifier in the main.py<\/code>, you can rename the module name to another as follows:<\/p>\n\n\n
import<\/span> pricing as<\/span> selling_price<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
And then you can use the selling_price<\/code> as the identifier in the main.py<\/code>:<\/p>\n\n\n
net_price = selling_price.get_net_price(\n    price=100<\/span>,\n    tax_rate=0.01<\/span>\n)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
from <module_name> import <name> #<\/a><\/h3>\n\n\n\n
If you want to reference objects in a module without prefixing the module name, you can explicitly import them using the following syntax:<\/p>\n\n\n
from<\/span> module_name import<\/span> fn1, fn2<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Now, you can use the imported functions without specifying the module name like this:<\/p>\n\n\n
fn1()\nfn2()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
This example imports the get_net_price()<\/code> function from the pricing<\/code> module:<\/p>\n\n\n
# main.py<\/span>\nfrom<\/span> pricing import<\/span> get_net_price<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
and use the get_net_price()<\/code> function from the pricing<\/code> module:<\/p>\n\n\n
# main.py<\/span>\nfrom<\/span> pricing import<\/span> get_net_price\n\nnet_price = get_net_price(price=100<\/span>, tax_rate=0.01<\/span>)\nprint(net_price)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
It’s possible to rename an imported name to another by using the following import<\/code> statement:<\/p>\n\n\n
from<\/span> <module_name> import<\/span> <name> as<\/span> <new_name><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The following example renames the get_net_price()<\/code> function from the pricing<\/code> module to calculate_net_price()<\/code> function:<\/p>\n\n\n
from<\/span> pricing import<\/span> get_net_price as<\/span> calculate_net_price\n\nnet_price = calculate_net_price(\n    price=100<\/span>,\n    tax_rate=0.1<\/span>,\n    discount=0.05<\/span>\n)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
from <module_name> import * : import all objects from a module #<\/a><\/h3>\n\n\n\n
To import every object from a module, you can use the following syntax:<\/p>\n\n\n
from<\/span> module_name import<\/span> *<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
However, it’s not a good practice because if the imported modules have the same object, the object from the second module will override the first one. The program may not work as you would expect.<\/p>\n\n\n\n
Let’s see the following example.<\/p>\n\n\n\n
First, create a new file called product.py<\/code> and define the get_tax()<\/code> function:<\/p>\n\n\n
# product.py<\/span>\ndef<\/span> get_tax<\/span>(price)<\/span>:<\/span>\n    return<\/span> price * 0.1<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Both product<\/code> and pricing<\/code> modules have the  get_tax()<\/code> function. However, the get_tax()<\/code> function from the product<\/code> module has only one parameter while the get_tax()<\/code> function from the pricing<\/code> module has two parameters.<\/p>\n\n\n\n
Second, import all objects from both pricing<\/code> and product<\/code> modules and use the get_tax()<\/code> function:<\/p>\n\n\n
from<\/span> pricing import<\/span> *\nfrom<\/span> product import<\/span> *\n\ntax = get_tax(100<\/span>)\nprint(tax)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Since the get_tax()<\/code> function from the product<\/code> module overrides the get_tax<\/code>() function from the pricing<\/code> module, you get the tax<\/code> with a value of 10.<\/p>\n\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
This import<\/code> statement will import all public identifiers including variables<\/a>, constants<\/a>, functions<\/a>, classes<\/a>, etc., to the program.<\/p>\n\n\n\n
This module name allows you to access functions, variables, etc. from the imported module in the current module. For example, you can call a function<\/a> defined in the imported module using the following syntax:<\/p>\n\n\n