**Course Title:** Modern Python Programming: Best Practices and Trends **Section Title:** Functions, Modules, and Best Practices **Topic:** Write modular code by creating functions and organizing them into modules. (Lab topic) **Objective:** By the end of this lab, you will be able to write modular code by creating functions and organizing them into modules, making your code more readable, maintainable, and reusable. **What is Modular Code?** Modular code is a programming approach where a large program is broken down into smaller, independent modules. Each module contains a set of related functions that perform a specific task. This approach makes code more readable, maintainable, and reusable. **Benefits of Modular Code** * **Readability**: Modular code is easier to read and understand because each module has a single responsibility. * **Maintainability**: When a bug occurs, it's easier to identify and fix the issue in a modular codebase. * **Reusability**: Modules can be reused in other parts of the program or even in other projects. **Creating Functions** Before we dive into creating modules, let's review how to create functions in Python. ```python def greet(name: str) -> None: print(f"Hello, {name}!") greet("John") # Output: Hello, John! ``` In the example above, we define a function called `greet` that takes a `name` parameter and prints a greeting message. **Creating Modules** A Python module is a file that contains a set of related functions, classes, and variables. To create a module, simply create a new Python file, for example, `math_utils.py`. ```python # math_utils.py def add(x: int, y: int) -> int: return x + y def multiply(x: int, y: int) -> int: return x * y ``` In the example above, we create a module called `math_utils` that contains two functions: `add` and `multiply`. **Importing Modules** To use functions from a module, we need to import the module first. There are two ways to import modules: ```python # Import the entire module import math_utils result = math_utils.add(2, 3) print(result) # Output: 5 # Import specific functions from the module from math_utils import add result = add(2, 3) print(result) # Output: 5 ``` **Package Structure** A package is a directory that contains a set of related modules. To create a package, create a directory and add a `__init__.py` file inside it. ```bash my_package/ __init__.py math_utils.py string_utils.py ``` **Best Practices** * **Keep each module focused on a single responsibility**. * **Use meaningful and descriptive names for modules and functions**. * **Use type hints to specify the types of function parameters and return values**. * **Write docstrings to document functions and modules**. **Lab Exercise** Create a module called `calculator` that contains four functions: `add`, `subtract`, `multiply`, and `divide`. Then, create a separate Python file that imports the `calculator` module and uses its functions to perform arithmetic operations. **Resources** * [Python Modules and Packages documentation](https://docs.python.org/3/tutorial/modules.html) * [Best Practices for Writing Python Modules](https://github.com/trekhleb/state-machine-cat/blob/master/readme/python-modules-best-practices.md) **What's Next** In the next topic, we will explore the basics of Object-Oriented Programming (OOP) in Python, including classes, objects, and methods. **Leave a Comment/Ask for Help** If you have any questions or need help with the lab exercise, please leave a comment below. We'll be happy to assist you.