Building a Command-Line Interface with Python

Python is a powerful scripting language that is well-suited for building command-line interfaces (CLI). In this post, we will explain how to build a CLI using Python.

Using the argparse Module

The argparse module, part of Python's standard library, makes it easy to build a CLI. It allows you to parse and handle command-line arguments.

Let's take a look at an example of building a simple CLI. In this example, we have a simple program that adds two numbers entered by the user.

First, import the argparse module:

import argparse

Next, create an ArgumentParser object and add arguments to it:

parser = argparse.ArgumentParser(description='Add two numbers.')
parser.add_argument('num1', type=int, help='First number')
parser.add_argument('num2', type=int, help='Second number')

Now, parse the command-line arguments and perform the addition:

args = parser.parse_args()
result = args.num1 + args.num2

Finally, print the result:

print(f'{args.num1} + {args.num2} = {result}')

Using the click Module

Another popular library for building CLIs in Python is click. It offers a more elegant and user-friendly interface than argparse. To use click, you need to install it first:

pip install click

Now let's create a simple CLI using click. We'll use the same example of adding two numbers:

import click

@click.command()
@click.argument('num1', type=int)
@click.argument('num2', type=int)
def add(num1, num2):
    result = num1 + num2
    print(f'{num1} + {num2} = {result}')

if __name__ == '__main__':
    add()

Conclusion

In this blog post, we explored how to build command-line interfaces using Python. We looked at two popular libraries for building CLIs: argparse, which is part of Python's standard library, and click, a third-party library. Both libraries offer a simple and effective way to create command-line interfaces in Python, allowing you to choose the one that best suits your needs.