"Python command-line argument parsing: Optparse module"

When you use Python for scripting, it is often necessary to invoke the Python script module in the form of a terminal interaction. At this time
Support for providing the underlying command-line parameters in a Python module is essential. So, in Python, how do we implement command-line arguments and parse it, the following is a brief introduction to this.

Python support for command-line argument parsing

Support for command-line argument parsing via two built-in modules in Python: getopt and Optparse

Two built-in support

Module Name	function Description
Getopt	Simple handling of command-line arguments
Optparse	The ability to handle complex command-line parameters and easily generate Unix-like help information is more powerful.

Basic use

Example code:

"""A simple usage example for optparse moduleBy Fat Boy."""from optparse import OptionParser  # Import the moduledef main():    opts = parse_command()    print("Param filename: " + opts.filename)    print("Param Debug: " + str(opts.debug))def parse_command():    parser = OptionParser()  # Initialize the OptionParser class    # Add commandline parameters format    parser.add_option("-f", "--filename", dest="filename",                      help="Set the output file name")    parser.add_option("-D", "--Debug",                      action="store_true", dest="debug", default=False,                      help="Set the debug switch")    # Parse the command params    (opts, args) = parser.parse_args()    return optsif __name__ == "__main__":    main()    

Test

Enter the following command in the terminal to execute the argv.py.

python argv.py --file=outfile -D

To view the results of the output:

Param filename: outfileParam Debug: True

Introduction to Key methods

"Add_option ()" is the most important method when processing command-line arguments based on the "Optparse" module

Optionparser Initialize Add_option () to define command-line arguments

parser.add_option("-D", "--Debug",                      action="store_true", dest="debug", default=False,                      help="Set the debug switch")

Parameter name	function	Description
Parameter 0	First argument, command-line argument short name	Reference code: "-D"
Parameter 1	Second argument, command-line argument long name	Reference code: "--debug"
Action	Indicates optparse how to handle the store, Store_true, Store_false, Store_const, Append, Count, callback when resolving to a command-line argument	Default to store
Dest	Set the name of the variable that stores the parameter value	What is stored is the content immediately following the argument
Type	Set the data type of the parameter	The default is string and can also be set: Int/float
Default	Set default values for parameters
Help	To set the Help description text for a parameter
Metavar	A value to remind the user that the parameter should be entered	Display as uppercase

Description

1. The value of the action parameter defaults to store, which represents the options object where the command-line arguments are stored.
   
2. Store_true and Store_false are generally used in cases where only the command has no value. Store_true indicates that the variable value defined by the Dest property is set to True when the command appears on the command line. Accordingly, Store_false indicates that the variable value defined by the Dest property is set to False when the command appears on the command line.

Parse_args ()

The method returns the parsed command-line parameter values, as shown in the following:

(opts, args) = parser.parse_args()

Users can pass opts. [dest The specified variable name] to obtain the parsed argument.

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"Python command-line argument parsing: Optparse module"