The functools module provides some useful tools for functions, including several decorators.
@wraps
@wraps
is useful when creating decorators.
It updates the new function to “look like” the original function.
(Script available)
from functools import wraps
def decorator(func):
@wraps(func)
def __new_func(*args, **kwargs):
# do stuff
return func(*args, **kwargs)
return __new_func
@decorator
def f():
"""
This is f!
:return:
"""
pass
if __name__ == '__main__':
help(f) # try removing the @wraps decorator
@lru_cache
@lru_cache
lets a function memorize its previous calls and their results,
eliminating the need to make repetitive calculations.
(Script available)
import sys
import time
from functools import lru_cache
@lru_cache()
def fibonacci(n):
print("Calculating {}".format(n), file=sys.stderr)
time.sleep(0.1)
if n <= 0:
return 0
if n == 1:
return 1
return fibonacci(n - 1) + fibonacci(n - 2)
if __name__ == '__main__':
print(fibonacci(10))
print(fibonacci(20))
There is also the “lru” aspect of the tool, which has a more detailed explanation in the docs.
@total_ordering
Doc:
Given a class defining one or more rich comparison ordering methods, this class decorator supplies the rest. This simplifies the effort involved in specifying all of the possible rich comparison operations:
The class must define one of
__lt__(),__le__(),__gt__(), or__ge__(). In addition, the class should supply an__eq__()method.
(Script available)
from functools import total_ordering
@total_ordering
class Integer(object):
def __init__(self, x):
self.x = x
def __eq__(self, other):
return self.x == other.x
def __lt__(self, other):
return self.x < other.x
if __name__ == '__main__':
print(Integer(1) >= Integer(2)) # try removing @total_ordering decorator