Create and Access a Python Package

In Python, a package is a way to organize related modules into a directory structure. Instead of keeping all files in one place, packages help group similar functionality together, making code easier to manage, reuse and maintain especially in large projects.

Creating a Package

Creating a package involves just three steps:

Create a directory (this will be package name)
Add Python files (modules) inside it
Add an __init__.py file to mark it as a package

Let's create a package named Cars and build three modules in it namely, Bmw, Audi and Nissan. Below is the folder structure:

cars/
│── __init__.py
│── bmw.py
│── audi.py
│── nissan.py

bmw.py: This module defines the BMW class, which contains a method to return a list of BMW car models.

Python

class BMW:
    def models(self):
        return ["i8", "X1", "X5"]

audi.py: This module defines the Audi class, which provides Audi car models through a method.

Python

class Audi:
    def models(self):
        return ["A3", "A6", "Q7"]

nissan.py: This module defines the Nissan class, used to return popular Nissan car models.

Python

class Nissan:
    def models(self):
        return ["Altima", "Rogue", "370Z"]

init.py: The __init__.py file makes the cars directory a package. By importing classes here, it allows direct access to BMW, Audi, and Nissan classes when the package is imported.

Python

from .bmw import BMW
from .audi import Audi
from .nissan import Nissan

This file allows direct access to classes when importing the package.

Accessing the Package

Now, create a file named main.py in the same directory where the cars package exists. This file will be used to import and access the classes defined inside the package modules.

Python

from cars import BMW, Audi, Nissan

bmw = BMW()
print(bmw.models())

audi = Audi()
print(audi.models())

nissan = Nissan()
print(nissan.models())

Output

['i8', 'X1', 'X5']
['A3', 'A6', 'Q7']
['Altima', 'Rogue', '370Z']

Explanation:

from cars import BMW, Audi, Nissan: imports the classes directly from the package using __init__.py.
BMW(), Audi(), and Nissan(): create objects of their respective classes.
models(): is called on each object to retrieve the list of car models.

Different Ways to Import from a Package

Python provides multiple ways to import content from a package depending on how much access you need.

1. Import a Specific Module: used when only one class or module is required from the package

from cars.bmw import BMW

This statement imports only the BMW class from the bmw module inside the cars package.

2. Import the Whole Package: used when modules need to be accessed using the package name

import cars

This statement imports the entire cars package, and its modules or classes must be accessed using dot notation.

3. Import Everything Using *: used to import all objects defined in __init__.py

from cars import *

This statement imports all classes and objects listed in the __init__.py file.

Note: This works only if objects are explicitly defined in __init__.py and is generally not recommended for large projects.

Create and Access a Python Package

Creating a Package

Accessing the Package

Different Ways to Import from a Package

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