argparse — Parser for command-line options, arguments and sub-commands

The argparse module makes it easy to write user-friendly command-line interfaces. The program defines what arguments it requires, and argparse will figure out how to parse those out of sys.argv. The argparse module also automatically generates help and usage messages and issues errors when users give the program invalid arguments.

Example

The following code is a Python program that takes a list of integers and produces either the sum or the max:

// An highlighted block
import argparse

parser = argparse.ArgumentParser(description='Process some integers.')
parser.add_argument('integers', metavar='N', type=int, nargs='+',
                    help='an integer for the accumulator')
parser.add_argument('--sum', dest='accumulate', action='store_const',
                    const=sum, default=max,
                    help='sum the integers (default: find the max)')

args = parser.parse_args()
print(args.accumulate(args.integers))

Assuming the Python code above is saved into a file called prog.py, it can be run at the command line and provides useful help messages:

$ python prog.py -h
usage: prog.py [-h] [--sum] N [N ...]

Process some integers.

positional arguments:
 N           an integer for the accumulator

optional arguments:
 -h, --help  show this help message and exit
 --sum       sum the integers (default: find the max)

When run with the appropriate arguments, it prints either the sum or the max of the command-line integers:

$ python prog.py 1 2 3 4
4

$ python prog.py 1 2 3 4 --sum
10

ArgumentParser objects

class argparse.ArgumentParser(prog=None, usage=None, description=None, epilog=None, parents=[], formatter_class=argparse.HelpFormatter, prefix_chars=’-’, fromfile_prefix_chars=None, argument_default=None, conflict_handler=‘error’, add_help=True, allow_abbrev=True)

• prog - The name of the program (default: sys.argv[0])
• usage - The string describing the program usage (default: generated from arguments added to parser)
• description - Text to display before the argument help (default: none)
• epilog - Text to display after the argument help (default: none)
• parents - A list of ArgumentParser objects whose arguments should also be included
• formatter_class - A class for customizing the help output
• prefix_chars - The set of characters that prefix optional arguments (default: ‘-‘)
• fromfile_prefix_chars - The set of characters that prefix files from which additional arguments should be read (default: None)
• argument_default - The global default value for arguments (default: None)
• conflict_handler - The strategy for resolving conflicting optionals (usually unnecessary)
• add_help - Add a -h/–help option to the parser (default: True)
• allow_abbrev - Allows long options to be abbreviated if the abbreviation is unambiguous. (default: True)

你可以找到更多关于的参数的详细介绍here.

The add_argument() method

ArgumentParser.add_argument(name or flags…[, action][, nargs][, const][, default][, type][, choices][, required][, help][, metavar][, dest])

• name or flags - Either a name or a list of option strings, e.g. foo or -f, --foo.
• action - The basic type of action to be taken when this argument is encountered at the command line.
• nargs - The number of command-line arguments that should be consumed.
• const - A constant value required by some action and nargs selections.
• default - The value produced if the argument is absent from the command line.
• type - The type to which the command-line argument should be converted.
• choices - A container of the allowable values for the argument.
• required - Whether or not the command-line option may be omitted (optionals only).
• help - A brief description of what the argument does.
• metavar - A name for the argument in usage messages.
• dest - The name of the attribute to be added to the object returned by parse_args().

你可以找到更多关于的参数的详细介绍here.

The parse_args() method

ArgumentParser.parse_args(args=None, namespace=None)

• args - List of strings to parse. The default is taken from sys.argv.
• namespace - An object to take the attributes. The default is a new empty Namespace object.

你可以找到更多关于的参数的详细介绍here.

References

[1]Python Doc