python_catchup_2024/4_decorators.py

"""
Now that we have covered the basics of a function and variables, we will quickly cover decorators.
Decorators are extremely useful and are used to wrap existing functions in another function, you can use this 
for many different things, a good example is permission checks.

Key Concepts:
    **wrappers** are used to nest functions in another generalized function, this can be used for various things e.g (logging info)
    **args** we use the "*args* paramater to capture all positional based arguements, these come before keyword arguements.
     it sounds more complicated than it is, e.g
     myfunction(arg1, arg2, arg3)
    **kwargs** are arguements defined by a key rather than their position. e.g
     myfunction(keyword1="foo", keyword2="bar")
    **__name__** is just another magic/dunder method that returns the function's name.
"""

import time
# Initial function takes in another function as a arguement
def timed(function: any) -> any:
     
    # The wrapper, takes in the arguements and keyword arguements from the function
    def wrapper(*args: any, **kwargs: any) -> any: 
        before = time.time()
        output = function(*args, **kwargs)
        after = time.time()
        print(f"{function.__name__} with output of {output} took {after-before}s to execute.")
        # Ensure the output of the function is passed back
        return output 
    
    return wrapper 

# Python uses @ to use a wrapper on a function
@timed
# O(n^2) time complexity due to nested loops
def exponential_function(n: int) -> int:  
    output = 0
    for i in range(n):
        for j in range(i):
            output += j
    return output

# Test the decorated function

# This will take some time to compute
exponential_function(1000) 

# This will take noticeably more time to compute
exponential_function(10000)