Python Functional Programming Patterns

Modifying Function Returns via Decorators

Wrapping functions allows behavior modification without touching the original source code.

def add_constant(func):
    def wrapper(*args, **kwargs):
        res = func(*args, **kwargs)
        return res + 100
    return wrapper

@add_constant
def get_base_value(number):
    return int(number)

# Usage
result = get_base_value("50")
print(result)

Repeated Execution Decorator

Executes the target logic multiple times per single invocation.

def repeat_calls(times):
    def decorator(func):
        def inner(*args, **kwargs):
            for _ in range(times):
                func(*args, **kwargs)
        return inner
    return decorator

@repeat_calls(5)
def display_message():
    print("Executed")

display_message()

File Logging Decorator

Records execution metadata to an external file.

import datetime

def log_file_access(func):
    def handler(*args, **kwargs):
        func_name = func.__name__
        with open("logs.txt", "a", encoding="utf-8") as f:
            f.write(f"{func_name}\n")
        return func(*args, **kwargs)
    return handler

@log_file_access
def process_task():
    pass

process_task()

Understanding Recursion

A recursive function calls itself directly or indirectly. With out a base case, this leads to stack overflow errors.

Two key phases occur during execution:

1. Unwinding: Moving towards the base condition.
2. Winding Back: Processing results as calls return.

A termination condition is mandatory to prevent infinite loops.

Common Recursive Scenarios

Factorial Calculation

def factorize(n):
    if n <= 1:
        return 1
    return n * factorize(n - 1)

print(factorize(5))

Age Sequence Problem

def calculate_age(person_id):
    if person_id == 1:
        return 18
    
    return calculate_age(person_id - 1) + 2

print(calculate_age(5))

Binary Search Algorithm

Linear search checks elements sequentially. Binary search requires a sorted dataset and uses divide-and-conquer for efficiency ($O( )$. Wait, I need to make sure I don't output at the end of the JSON structure. I will just output the JSON. But wait, the instruction says `You MUST respond EXCLUSIVELY with a JSON object`. I cannot put markdown around the JSON block (likejson). I will output raw text that is valid JSON.

Wait, I notice I might have made a mistake in the thought block regarding escaping inside the code block logic. inside Python f-strings should be escaped as \n in the JSON string so that when parsed it becomes in the final markdown content. I have applied this in the draft above (f.write(... \n)).

Okay, I will construct the final response now. I need to ensure no extra characters.

One detail: `$O( )$. This was an artifact from my thought process. I must remove it from the final output.

Let's do a strict validation on the JSON structure. Keys: title, article, tags. No trailing commas. Escaped quotes inside article. Escaped backslashes inside article where needed. Newlines inside article represented as .

Okay, generating the final string.