How does importing modules work in Python?

A module is a file with a .py extension containing Python code (functions, classes, variables). Modules help organize and reuse code.

Ways to import:

# Importing an entire module
import math
print(math.sqrt(16))  # 4.0

# Importing specific objects
from math import sqrt, pi
print(sqrt(16))  # 4.0

# Importing with an alias
import datetime as dt
now = dt.datetime.now()

Creating your own module:

# utils.py
def greet(name):
    return f"Hello, {name}!"

# main.py
from utils import greet
print(greet("World"))

__name__ == "__main__":

Allows distinguishing whether the file is run directly or imported as a module:

# my_module.py
def main():
    print("Running the module directly")

if __name__ == "__main__":
    # This code executes only when running directly:
    # python my_module.py
    main()

Packages:

A package is a directory with an __init__.py file containing multiple modules:

my_package/
    __init__.py
    module_a.py
    module_b.py

from my_package.module_a import some_function