Decorators

Problem 1: Timing Function Execution

Problem: Write a decorator that measures the time a function takes to execute.

import time

def timer(func):
    def wrapper(*args, **kwargs):
        start = time.time()
        result = func(*args, **kwargs)
        end = time.time()
        print(f"{func.__name__} ran in {end-start} times")
        return result
    return wrapper

@timer

def example_function(n):
    time.sleep(n)

example_function(2)

Problem 2: Debugging Function Calls

Problem: Create a decorator to print the function name and the values of its arguments every time the function is called.

def debug(func):
    def wrapper(*args, **kwargs):
        args_value = ', '.join(str(arg) for arg in args)
        kwargs_value = ', '.join(f"{k}={v}"for k, v in kwargs.items())
        print(f"calling: {func.__name__} with args {args_value} and kwargs {kwargs_value}")
        return func(*args, **kwargs)
    return wrapper

@debug
def hello():
    print("Hello")


@debug

def greet(name, greeting="Hello"):
    print(f"{greeting}, {name}")


hello()
greet("chai", greeting="hanji")

Problem 3: Cache Return Values

Problem: Implement a decorator that caches the return values of a function, so that when it’s called with the same arguments, the cached value is returned instead of re-executing the function.

import time

def cache(func):
    cache_value = {}
    print(cache_value)

    def wrapper(*args):
        if args in cache_value:
            return cache_value[args]
        result = func(*args)
        cache_value[args] = result
        return result
    return wrapper
@cache

def lon_running_function(a, b):
    time.sleep(4)
    return a + b

print(lon_running_function(2, 3))
print(lon_running_function(3, 3))
print(lon_running_function(4, 3))