function_demonstrator

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Filename: function_demonstrator.py
# Version: 1.0.0
# Author: Jeoi Reqi

"""
Description:
    - This Python script demonstrates various common programming tasks through a user-friendly menu-driven interface.
    - Users can interact with different functions, gaining hands-on experience and understanding of their functionality.
    - Functions cover tasks from simple greetings to complex operations like string concatenation and numerical calculations.
    - Presented in a menu driven format, users can explore and understand functions easily.
    - This script serves as a valuable resource for learners and a reference for experienced programmers.
    - The script offers a clear and intuitive interface, allowing users to navigate effortlessly and interact through prompts.
    - It gracefully handles user input, ensuring a smooth experience even for those with minimal programming knowledge.
    - No matter your programming skill level, this script offers an accessible way to engage with fundamental programming concepts.

Requirements:
    - Python 3.x
    - From typing module: (List, Optional, Dict, Tuple, Callable functions)

Functions:
    - Greet:
        Function with no arguments and no return value. Prints a greeting message.
    - Display Message:
        Function with arguments and no return value. Prints the given message.
    - Add:
        Function with arguments and a return value. Returns the sum of two numbers.
    - Concat Strings:
        Function with multiple argument types and a return value. Concatenates two strings.
    - Sum List:
        Function with a list argument and a return value. Returns the sum of all elements in the list.
    - Find Element:
        Function with a list argument and an optional target value. Finds the index of the target element in the list. Returns None if not found.
    - Get Value:
        Function with a dictionary argument and a return value. Returns the value associated with the key in the dictionary, or 0 if not found.
    - Swap Values:
        Function with a tuple argument and a return value. Swaps the two values in the tuple.
    - Apply Function:
        Function with a callable argument and two integer arguments. Applies the given function to the two integer arguments.

Usage:
    - Run the script and choose an option from the displayed menu.
    - Follow the prompts to interact with each function.

Example Output:

                _________________________

                   :: Function Menu ::
                _________________________

                1. Greet
                2. Display Message
                3. Add
                4. Concat Strings
                5. Sum List
                6. Find Element
                7. Get Value
                8. Swap Values
                9. Apply Function
                0. Exit
                _________________________

                Choose an option: 4
                _________________________

                    - Function with multiple argument types and a return value.
                    - Concatenates two strings.

                Enter first string:  this+
                Enter second string: that

                Result: this+that

Additional Notes:
    - For functions with optional arguments, if the argument is not provided, a default value or behavior is assumed.
    - Ensure to input valid data types as required by each function to avoid errors.
"""


from typing import List, Optional, Dict, Tuple, Callable

def greet() -> None:
    """
    - Function with no arguments and no return value.
    - Prints a greeting message.
    """
    print("Hello, world!")

def display_message(message: str) -> None:
    """
    - Function with arguments and no return value.
    - Prints the given message.
    """
    print(message)

def add(a: int, b: int) -> int:
    """
    - Function with arguments and a return value.
    - Returns the sum of a and b.
    """
    return a + b

def concat_strings(a: str, b: str) -> str:
    """
    - Function with multiple argument types and a return value.
    - Concatenates two strings.
    """
    return a + b

def sum_list(numbers: List[int]) -> int:
    """
    - Function with a list argument and a return value.
    - Returns the sum of all elements in the list.
    """
    return sum(numbers)

def find_element(elements: List[int], target: int) -> Optional[int]:
    """
    - Function with an optional argument.
    - Finds the index of the target element in the list. Returns None if not found.
    """
    try:
        return elements.index(target)
    except ValueError:
        return None

def get_value(data: Dict[str, int], key: str) -> int:
    """
    - Function with a dictionary argument.
    - Returns the value associated with the key in the dictionary, or 0 if not found.
    """
    return data.get(key, 0)

def swap_values(pair: Tuple[int, int]) -> Tuple[int, int]:
    """
    - Function with a tuple argument and a return value.
    - Swaps the two values in the tuple.
    """
    return pair[1], pair[0]

def apply_function(f: Callable[[int, int], int], x: int, y: int) -> int:
    """
    - Function with a callable argument.
    - Applies the given function to x and y.
    """
    return f(x, y)

# Print a separator line
def line():
    print("_" * 25)

def main():
    while True:
        line()                                                               # Print a separator line
        print("\n   :: Function Menu ::")                                    # Print the menu title
        line()
        print("\n1. Greet")
        print("2. Display Message")
        print("3. Add")
        print("4. Concat Strings")
        print("5. Sum List")
        print("6. Find Element")
        print("7. Get Value")
        print("8. Swap Values")
        print("9. Apply Function")
        print("0. Exit")

        line()
        choice = input("\nChoose an option: ")                               # Prompt the user to choose an option
        line()

        if choice == '1':
            print()
            print(greet.__doc__)                                             # Print the documentation for the greet function
            print()
            print("Result: ", end='')                                        # Print "Result: " without newline
            greet()                                                          # Call the greet function
            print()                                                          # Print a newline
        elif choice == '2':
            print()
            print(display_message.__doc__)                                   # Print the documentation for the display_message function
            print()
            message = input("Enter a message: ")                             # Prompt the user to enter a message
            print()
            print(f"Result: {message}")                                      # Print the entered message
            print()
        elif choice == '3':
            print(add.__doc__)                                               # Print the documentation for the add function
            a = int(input("Enter first number:  "))                          # Prompt the user to enter the first number
            b = int(input("Enter second number: "))                          # Prompt the user to enter the second number
            print("\nResult:", add(a, b))                                    # Print the result of adding the two numbers
        elif choice == '4':
            print(concat_strings.__doc__)                                    # Print the documentation for the concat_strings function
            first_string: str = input("Enter first string:  ")               # Prompt the user to enter the first string
            second_string: str = input("Enter second string: ")              # Prompt the user to enter the second string
            print("\nResult:", concat_strings(first_string, second_string))  # Print the result of concatenating the strings
        elif choice == '5':
            print(sum_list.__doc__)                                          # Print the documentation for the sum_list function
                                                                             # Prompt the user to enter numbers
            numbers = list(map(int, input("Enter numbers separated by space: ").split()))
            print("\nResult:", sum_list(numbers))                            # Print the sum of the numbers
        elif choice == '6':
            print(find_element.__doc__)                                      # Print the documentation for the find_element function
                                                                             # Prompt the user to enter numerical elements
            elements = list(map(int, input("Enter numerical elements separated by space: ").split()))
            target = int(input("Enter target element: "))                    # Prompt the user to enter the target element
            result = find_element(elements, target)                          # Find the target element in the list
                                                                             # Print the result of finding the element
            print("\nResult:", "Element found at index " + str(result) if result is not None else "Element not found")
        elif choice == '7':
            print(get_value.__doc__)                                         # Print the documentation for the get_value function
            data = {'a': 42, 'b': 69, 'c': 420}                              # Define a dictionary of numerical values
            key = input("Enter key (a, b, or c): ")                          # Prompt the user to enter a key
            print("\nResult:", get_value(data, key))                         # Print the value associated with the key in the dictionary
        elif choice == '8':
            print(swap_values.__doc__)                                       # Print the documentation for the swap_values function
            x = int(input("Enter first value:  "))                           # Prompt the user to enter the first value
            y = int(input("Enter second value: "))                           # Prompt the user to enter the second value
            print("\nResult:", swap_values((x, y)))                          # Print the result of swapping the values
        elif choice == '9':
            print(apply_function.__doc__)                                    # Print the documentation for the apply_function function
            x = int(input("Enter first number:  "))                          # Prompt the user to enter the first number
            y = int(input("Enter second number: "))                          # Prompt the user to enter the second number
            print("\nResult:", apply_function(add, x, y))                    # Print the result of applying the function to the numbers
        elif choice == '0':
            print("\n  Exiting...   GoodBye!")                               # Print an exit message
            line()                                                           # Print a separator line
            break
        else:
            print("Invalid choice. Please try again.")                       # Print an error message for invalid choices

if __name__ == "__main__":
    main()