How to make a parser on Python

Learn how to create a Python parser using an example. Create efficient, flexible code to process data from any source.

Creating a Parser in Python

Creating a parser in Python is relatively straightforward. Python has a built-in library called argparse that has functions for handling command-line arguments. This library can be used to create a parser for handling command-line arguments for a Python program. To demonstrate how to create a parser, we will create a program that takes two arguments: an operation (add, subtract, multiply, or divide) and two numbers. The program will then perform the operation on the two numbers and display the result.

import argparse

# Create the parser
parser = argparse.ArgumentParser(description="Calculator")

# Add the parameters
parser.add_argument("operation", help="The operation to perform: add, subtract, multiply, or divide")
parser.add_argument("first_number", type=int, help="The first number")
parser.add_argument("second_number", type=int, help="The second number")

# Parse the arguments
args = parser.parse_args()

# Perform the operation
if args.operation == "add":
    result = args.first_number + args.second_number
elif args.operation == "subtract":
    result = args.first_number - args.second_number
elif args.operation == "multiply":
    result = args.first_number * args.second_number
elif args.operation == "divide":
    result = args.first_number / args.second_number

# Display the result
print(result)

The code above creates a parser that handles command-line arguments for a calculator program. The parser takes three arguments: an operation (add, subtract, multiply, or divide), and two numbers. The parser then uses the operation argument to determine which operation to perform on the two numbers. The result is then printed out.

Using the argparse library makes it easy to create parsers for Python programs. By using the library, you can quickly create parsers that handle command-line arguments and perform the desired operations on the arguments.