Python command-line parsing tool argparse module "1"

Argpaser is a very useful command-line parsing module in Python, which makes it easy to create user-friendly command-line programs. and Argparse automatically generates help messages and error messages.

One, example

For example, take a few integers from the command line, and then get their and or their maximum values.

ImportArgparseparser= 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', the const=sum, default=Max, help='sum the integers (default:find the max)') args=Parser.parse_args ()PrintArgs.accumulate (Args.integers)

Entering prog.py-h from the command line displays the following information

$ prog.py-husage:prog.py [-h] [--sum] N [n ...] Process some integers.positional arguments:n           for-H,--help and  -- Sum       sum the integers (default:find the max)

If you use the appropriate parameters, you can also sum or get the maximum value.

$ prog.py 1 2 31 2 3 4--sum10

If an incorrect argument is passed, an error message is returned.

$ prog.py a b cusage:prog.py [-h] [--'a'

Here we explain this example in detail: 1. Create parserFirst, create a Argumentparser object.

>>> parser = Argparse. Argumentparser (description='Process some integers. ')

The Argumentparser object holds the necessary information to parse the command-line arguments. 2. Adding ParametersThe parameters in the command line are saved to the Argumentparser object by calling the Add_argument () method.

>>> 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)')

Calling Parse_args () later will return an object that contains the two properties of integers and accumulate, integers is a list, and accumulate can be the sum () function (if--sum is specified) or the max () function.

3. Parsing parameters

    Returns a Namespace object by parsing the parameter with the Parse_args () method.

>>> Parser.parse_args (['--sum'7'- 1"]) Namespace (accumulate=<built-in function Sum>, integers=[7,-1, 42])

If this function is called in a script, Parse_args () will not parse any parameters. Argumentparser automatically detects command-line arguments from the SYS.ARGV.

Python command-line parsing tool argparse module "1"