8 Levels of Writing Python Functions

Level 1: Basic Function Definition

Goal: Learn how to define simple functions with def.

def greet():
    return "Hello, World!"
        

Concepts: Function definition, return statement, and basic usage.

Level 2: Function Arguments

Goal: Understand how to pass data to functions using arguments.

def greet(name):
    return f"Hello, {name}!"
        

Concepts: Positional arguments, basic string formatting.

Level 3: Default Arguments

Goal: Use default argument values to make functions more flexible.

def greet(name="World"):
    return f"Hello, {name}!"
        

Concepts: Default values, handling optional parameters.

Level 4: Variable-Length Arguments

Goal: Handle an arbitrary number of arguments using args and *kwargs.

def greet(*names):
    return "Hello, " + ", ".join(names) + "!"
        

Concepts: args for positional arguments, *kwargs for keyword arguments.

Level 5: Return Multiple Values

Goal: Return multiple values from a function using tuples.

def divide(a, b):
    quotient = a // b
    remainder = a % b
    return quotient, remainder
    
        

Concepts: Tuple unpacking, returning multiple values.

Level 6: First-Class Functions

Goal: Treat functions as first-class citizens by passing them as arguments or returning them.

def apply_function(func, value):
    return func(value)

def square(x):
    return x * x

result = apply_function(square, 5)
        

Concepts: Functions as arguments, higher-order functions.

Level 7: Lambda Functions

Goal: Use lambda expressions for short, unnamed functions.

def apply_function(func, value):
    return func(value)

result = apply_function(lambda x: x * x, 5)
        

Concepts: Lambda expressions, anonymous functions.

Level 8: Decorators

Goal: Modify the behavior of functions using decorators.

def decorator(func):
    def wrapper(*args, **kwargs):
        print("Before the function")
        result = func(*args, **kwargs)
        print("After the function")
        return result
    return wrapper

@decorator
def greet(name):
    return f"Hello, {name}!"

greet("World")
        

Before the function
After the function
        

'Hello, World!'        

Concepts: Decorators, wrapping functions, modifying behavior.