Argparse
Argparse is a user-friendly command line interface. The argparse module parses the command-line arguments and options/flags.
Installation:
There many ways to install argparse module, the easy way is by using pip
$ pip install argparse
Initialize Argparse
import argparse parser=argparse.ArgumentParser(description="Program description")
Adding positional/optional arguments: Using add_argument() we can add positional/optional parameters to the parser.
parser.add_argument(‘-parameterName’,’–optionalName’,help=”message”)
Here, -parameterName is a short hand notation.
–optionalName is the optional parameter.
-h –help monitors the help.
Command Line Usage
$ python [file].py [command] [options] name
Example:
Python3
# argparse_example.pyimport argparseif __name__=='__main__': #Initialize parser=argparse.ArgumentParser(description="Simple calculator") #Adding optional parameters parser.add_argument('-n1', '--num1', help="Number 1", type=float) parser.add_argument('-n2', '--num2', help="Number 2", type=float) parser.add_argument('-op', '--operation', help="operator", default="*") #Parsing the argument args=parser.parse_args() print(args) #Initialize result to None result =None #Simple calculator operations if args.operation == '+': result=args.num1+args.num2 if args.operation == '-': result=args.num1-args.num2 if args.operation == '/': result=args.num1/args.num2 if args.operation == '*': result=args.num1*args.num2 if args.operation == 'pow': result=pow(args.num1,args.num2) #Print the result print("Result = " ,result) |
Output:
Argparse VS Docopt VS Click – Comparing Python Command-Line Parsing Libraries
Before knowing about the Python parsing libraries we must have prior knowledge about Command Line User Interface. A Command Line Interface (CLI) provides a user-friendly interface for the Command-line programs, which is most commonly favored by the developers or the programmers who prefer keyboard programming, instead of using the mouse. By building Command-line interfaces user can interact through the consoles, shells or terminals more efficiently.
There are plenty of Python libraries to build command line applications such as Argparse, Docopt, Click, Client and many more. Now, let us know more on frequently used Python libraries – Argparse, Docopt and Click.