Prefer argparse Over sys.argv for Command-line Arguments

Hi Pythonistas!

When writing Python scripts, we often want to pass arguments from the command line. While sys.argv is the simplest way, it's not the best tool for the job.

using sys.argv

import sys
name = sys.argv[1]
print(f"Hello, {name}!")

Problems:

No built-in help messages.
Manual index management.
No default values.
No type validation.
Hard to handle optional vs positional args.

The Better Way — argparse

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--name', default='Guest')
args = parser.parse_args()
print(f"Hello, {args.name}!")

Now you can run:

python script.py --name Harry

Or just:

python script.py

And it defaults to:

Hello, Guest!

Positional vs Optional Arguments

argparse supports both positional and optional arguments

Positional Argument - Defined without dashes

parser.add_argument('filename') # required positional argument

Run with:

python script.py file.txt

If you don’t supply it, argparse throws an error.

Optional Argument - Defined with dashes

parser.add_argument('--name', default='Guest')

Run with:

python script.py --name Harry

If omitted, it uses the default value (Guest).

Bonus: Built-in Help

python script.py --help

You get this for free:

usage: script.py [-h] [--name NAME]
optional arguments:
  -h, --help    show this help message and exit
  --name NAME   your name (default: Guest)

Why Prefer argparse?

Cleaner code
Auto-generated help
Input validation
Default values
Explicit positional vs optional control

please share your valuable suggestions with afsal@parseltongue.co.in