我如何使用argparse制作一个Python3文件来读取文件内容？

Question

I'm kind of a Python noob at the moment as I've only been using it for aa few days and I was wondering how would you write a Python script that uses argparse to read the contents of a file containing numerous URLs and set the contents as a variable? For example:

root@user:~# python myscript.py -f "URLs.txt"

and the python shell would then print the variable

URLs = The contents of the file
print(URLs)

resulting in:

root@user:~# python myscript.py -f "URLs.txt"
https://stackoverflow.com/
https://stackoverflow.com/
https://stackoverflow.com/
root@user:~#

Any help would be greatly appreciated!

Answer 1

For a start I'd recommend:

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('-f', '--foo')
args = parser.parse_args()
with open(args.foo, 'r') as f:
    lines = f.read()
    print(lines)

which with a ramdom file in my directory produces:

0029:~/mypy$ python stack47119114.py -f foo.txt
    1,    2,     
    3,    4,    5

We could use a argparse.FileType to open the file as well, but the with open syntax is preferable. For a larger problem I'd put the parse_args in a if __name__... block, and define the action in a function.

But the basic point is that argparse should be used primarily has a parser, not the full action code. Its purpose is to find out what your user wants. In a real problem, acting on that input is the job of functions and classes that are defined separately (maybe even in an imported module).