tiny_python_projects/appendix_argparse/cat_n_manual.py at master · lucyyangruo/tiny_python_projects · GitHub

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#!/usr/bin/env python3

"""Python version of `cat -n`, manually checking file argument"""

import argparse

import os

# --------------------------------------------------

def get_args():

"""Get command-line arguments"""

parser = argparse.ArgumentParser(

description='Python version of `cat -n`',

formatter_class=argparse.ArgumentDefaultsHelpFormatter)

parser.add_argument('file', metavar='str', type=str, help='Input file')

args = parser.parse_args()

if not os.path.isfile(args.file):

parser.error(f'"{args.file}" is not a file')

args.file = open(args.file)

return args

# --------------------------------------------------

def main():

"""Make a jazz noise here"""

args = get_args()

for i, line in enumerate(args.file, start=1):

print(f'{i:6} {line}', end='')

# --------------------------------------------------

if __name__ == '__main__':

main()

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