argparse–Parser for command-line options

1. Example

import argparse

parser = argparse.ArugumentParser()
parser.add_argument('-s', '--long', type=int, nargs='?', const = 12, default = 12)
settings = parser.parse_args()
print (settings.long)

2. ArgumentParser objects

class argparse.ArgumentParser([description][, epilog][, prog][, usage][, add_help][, argument_default][, parents][, prefix_chars][, conflict_handler][, formatter_class])

Create a new ArgumentParser object. Each parameter has its own more detailed description below, but in short they are:

• description - Text to display before the argument help.
• epilog - Text to display after the argument help.
• add_help - Add a -h/–help option to the parser. (default: True)
• argument_default - Set the global default value for arguments. (default: None)
• parents - A list of ArgumentParser objects whose arguments should also be included.
• 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)
• formatter_class - A class for customizing the help output.
• conflict_handler - Usually unnecessary, defines strategy for resolving conflicting optionals.
• prog - The name of the program (default: sys.argv[0])
• usage - The string describing the program usage (default: generated)

3. add_argument() method

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

Define how a single command-line argument should be parsed. Each parameter has its own more detailed description below, but in short they are:

• 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().

4. parse_args() method

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

Convert argument strings to objects and assign them as attributes of the namespace. Return the populated namespace.

Previous calls to add_argument() determine exactly what objects are created and how they are assigned. See the documentation for add_argument() for details.

By default, the arg strings are taken from sys.argv, and a new empty Namespace object is created for the attributes.

5. Sub-commands

to be continued.

转载于:https://www.cnblogs.com/kongs/archive/2011/11/17/2252522.html