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author | Raymond Hettinger <rhettinger@users.noreply.github.com> | 2019-11-18 06:06:19 (GMT) |
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committer | GitHub <noreply@github.com> | 2019-11-18 06:06:19 (GMT) |
commit | 04c79d6088a22d467f04dbe438050c26de22fa85 (patch) | |
tree | 4066a5d93a0569adb371e229724f59be78470ffe /Doc/tutorial/stdlib.rst | |
parent | 4544e78ec4558b75bf95e5b7dfc1b5bbb07ae5f0 (diff) | |
download | cpython-04c79d6088a22d467f04dbe438050c26de22fa85.zip cpython-04c79d6088a22d467f04dbe438050c26de22fa85.tar.gz cpython-04c79d6088a22d467f04dbe438050c26de22fa85.tar.bz2 |
bpo-38678: Improve argparse example in tutorial (GH-17207)
Diffstat (limited to 'Doc/tutorial/stdlib.rst')
-rw-r--r-- | Doc/tutorial/stdlib.rst | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/Doc/tutorial/stdlib.rst b/Doc/tutorial/stdlib.rst index f32063e..a52653b 100644 --- a/Doc/tutorial/stdlib.rst +++ b/Doc/tutorial/stdlib.rst @@ -72,21 +72,23 @@ three`` at the command line:: >>> print(sys.argv) ['demo.py', 'one', 'two', 'three'] -The :mod:`argparse` module provides a mechanism to process command line arguments. -It should always be preferred over directly processing ``sys.argv`` manually. - -Take, for example, the below snippet of code:: - - >>> import argparse - >>> from getpass import getuser - >>> parser = argparse.ArgumentParser(description='An argparse example.') - >>> parser.add_argument('name', nargs='?', default=getuser(), help='The name of someone to greet.') - >>> parser.add_argument('--verbose', '-v', action='count') - >>> args = parser.parse_args() - >>> greeting = ["Hi", "Hello", "Greetings! its very nice to meet you"][args.verbose % 3] - >>> print(f'{greeting}, {args.name}') - >>> if not args.verbose: - >>> print('Try running this again with multiple "-v" flags!') +The :mod:`argparse` module provides a more sophisticated mechanism to process +command line arguments. The following script extracts one or more filenames +and an optional number of lines to be displayed:: + + import argparse + + parser = argparse.ArgumentParser(prog = 'top', + description = 'Show top lines from each file') + parser.add_argument('filenames', nargs='+') + parser.add_argument('-l', '--lines', type=int, default=10) + args = parser.parse_args() + print(args) + +When run at the command line with ``python top.py --lines=5 alpha.txt +beta.txt``, the script sets ``args.lines`` to ``5`` and ``args.filenames`` +to ``['alpha.txt', 'beta.txt']``. + .. _tut-stderr: |