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Functions & basics

Reusable building blocks — parameters, returns, scope, and clear function design.

3 matches

How to Build a Subcommand Parser Tree with argparse in Python

Create a CLI with nested subcommands (like git) using argparse subparsers, where each subcommand maps to its own handler function.

argparse cli subparsers

Python

import argparse


def cmd_add(args):
    print(f"Adding {args.num1} + {args.num2} = {args.num1 + args.num2}")


def cmd_sub(args):
    print(f"Subtracting {args.num1} - {args.num2} = {args.num1 - args.num2}")


def main():
    parser = argparse.ArgumentParser(prog="calculator")
    subparsers = parser.add_subparsers(d…

12 0 Open

Functions & basics easy

How to Pass a Function as a Callback to map and filter in Python

Shows how to apply custom functions to every element of a list using map and filter callbacks in Python.

map filter callbacks

Python

def double(x):
    return x * 2

def is_even(x):
    return x % 2 == 0

if __name__ == "__main__":
    numbers = [1, 2, 3, 4, 5]
    doubled = list(map(double, numbers))
    evens = list(filter(is_even, numbers))
    print("Original:", numbers)
    print("Doubled:", doubled)
    print("Evens:", evens)

16 0 Open

Functions & basics easy

How to Use a Dispatch Table in Python (Map Strings to Functions)

Maps string command names to callable functions in a dictionary, then dispatches calls safely with error handling.

dispatch-table dictionary functions

Python

def add(a, b):
    return a + b


def subtract(a, b):
    return a - b


def multiply(a, b):
    return a * b


def divide(a, b):
    if b == 0:
        raise ValueError("Division by zero")
    return a / b


dispatch = {
    "add": add,
    "subtract": subtract,
    "multiply": multiply,
    "divide": divide,
}


def…

13 0 Open

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