Introduction

Welcome to the argparse-example-script repository! This script demonstrates a simple yet powerful command-line utility written in Python using the argparse library. It allows users to input personal information and formats it into a human-readable sentence.

What is argparse:

argparse is a module in Python’s standard library used for parsing command-line arguments. It provides a way to handle command-line inputs to your Python scripts, allowing users to specify options and arguments when running the script. This module simplifies the process of writing user-friendly command-line interfaces for Python programs.

import argparse

Features

• Name Input: Accepts a first name using the -n or --name flag.
• Family Name Input: Accepts a family name using the -f or --family flag.
• Age Input: Accepts an age using the -a or --age flag.
• Strict Flag Validation: Only exact flags (-n, --name, -f, --family, -a, --age) are allowed. Abbreviated or unknown flags will result in an error.

Common Method

• add_argument(name_or_flags, **kwargs): Defines what arguments the program is expecting. name_or_flags can be a string for a positional argument or a list of strings for optional arguments.

parser.add_argument('-n', '--name', type=str, help='Your first name.')
parser.add_argument('-f', '--family', type=str, help='Your family.')
parser.add_argument('-a', '--age', type=int, help='Your age.')

• parse_args(args=None): Parses the command-line arguments. args can be a list of strings to override default argument parsing.

Explanation:

1. Abbreviation Disabled:

• allow_abbrev=False ensures that the flags must be used exactly as defined (e.g., --name cannot be abbreviated as --na).

2. Error Handling:

• The script catches SystemExit to handle cases where invalid arguments are provided. This is useful for customizing the error message or further handling invalid inputs.

3. Output Construction:

• The script builds the output string based on which arguments are provided. It checks if name is provided first, then appends family and age as needed.

4. Graceful Fallback:

• If only family or age is provided without name, the script handles these cases separately, ensuring correct output formatting.

Usage

To use the script, you need to provide the required flags with their corresponding values. Here’s how you can run the script from the command line:

python main.py -n <FirstName> -f <FamilyName> -a <Age>

Example

• All Information Provided:

python main.py -n Alireza -f Malekzadeh -a 24

Output:

I am Alireza Malekzadeh, I am 24 years old.

• Name and Family Only:

python main.py -n Alireza -f Malekzadeh

Output:

I am Alireza Malekzadeh

• Only name:

python main.py -n Alireza

Output:

I am Alireza 

• Only Age:

python main.py -a 24

Output:

I am 24

Requirements

• Python 3.x
• argparse (included in the Python standard library)

Refined Script:

import argparse

# Create the argument parser with abbreviation disabled
parser = argparse.ArgumentParser(description='Example script.', allow_abbrev=False)

# Define the command-line arguments
parser.add_argument('-n', '--name', type=str, help='Your first name.')
parser.add_argument('-f', '--family', type=str, help='Your family name.')
parser.add_argument('-a', '--age', type=int, help='Your age.')

try:
    # Parse the command-line arguments
    args = parser.parse_args()
except SystemExit:
    # Handle invalid command-line usage
    print("Invalid command")
    exit()

# Initialize the output string
output = ""

# Construct the output based on provided arguments
if args.name:
    output += f"I am {args.name}"
    if args.family:
        output += f" {args.family}"
    if args.age:
        output += f", I am {args.age} years old."
elif args.family:
    output = f"I am {args.family}."
elif args.age:
    output = f"I am {args.age} years old."

# Print the result
print(output)

Conclusion

argparse is a powerful tool for handling command-line arguments in Python scripts. It simplifies argument parsing, helps manage script inputs, and provides a better user experience by generating help messages and handling errors gracefully.