Back
Close

Journey to Master Python (WIP)

ageekymonk
8,220 views

Decorators

Decorator is a syntactic sugar for higher order functions. Higher order functions take a function as input and return another function. It extends the functionality of the input function for fun and profit

For programmers print is best tool for debugging. In the example below the decorator is used to print the input and output of a function. Just adding the decorator to functions will do the job rather than going inside the function and adding a print and it is reusable.

Decorators
def debug_input_output(f):
def wrapping_function(*args, **kwargs):
print(f'Input: {args} {kwargs}')
ret = f(*args, **kwargs)
print(f'Output: {ret}')
return ret
return wrapping_function
@debug_input_output
def addressbook(name, **details):
"""My addressbook"""
return {'name': name, **details}
addressbook('jason', age=40, address='unknown')
print(addressbook.__name__)
print(addressbook.__doc__)
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

This implementataion of decorator has two problems.

  1. Name of the function is wrong
  2. Docstring is wrong.

Better Decorator using functools

Functools module provide necessary wrapper to write your own custom decorator. @wraps takes care of writing all the boiler plate code for retaining the name of the function and docstring. This is an improvement on our earlier implementataion.

Custom Decorator
from functools import wraps
import time
def timeme(f):
@wraps(f)
def wrapper(*args, **kwargs):
time1 = time.clock()
f(*args, **kwargs)
time2 = time.clock()
print(f'It took {(time2 - time1)*1000} ms to complete {f.__name__}')
return wrapper
@timeme
def myfunc():
""" My function to sleep"""
time.sleep(1)
print("Inside myfunc")
myfunc()
print(myfunc.__doc__)
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Create your playground on Tech.io
This playground was created on Tech.io, our hands-on, knowledge-sharing platform for developers.
Go to tech.io
codingame x discord
Join the CodinGame community on Discord to chat about puzzle contributions, challenges, streams, blog articles - all that good stuff!
JOIN US ON DISCORD
Online Participants