问题描述
我想可选的参数传递给在python我的课的装饰。
低于code我目前有：
I'm trying to pass optional arguments to my class decorator in python.Below the code I currently have:
class Cache(object):
def __init__(self, function, max_hits=10, timeout=5):
self.function = function
self.max_hits = max_hits
self.timeout = timeout
self.cache = {}
def __call__(self, *args):
# Here the code returning the correct thing.
@Cache
def double(x):
return x * 2
@Cache(max_hits=100, timeout=50)
def double(x):
return x * 2
第二个装饰用的参数覆盖默认的（ max_hits = 10，超时= 5 在我的 __的init __ 功能），不能正常工作，我得到异常类型错误：__init __（）至少需要2个参数（3给出）。我尝试了许多解决方案，并了解它的文章，但在这里我仍然不能使它发挥作用。
The second decorator with arguments to overwrite the default one (max_hits=10, timeout=5 in my __init__ function), is not working and I got the exception TypeError: __init__() takes at least 2 arguments (3 given). I tried many solutions and read articles about it, but here I still can't make it work.
任何想法解决这个？谢谢！
Any idea to resolve this? Thanks!
推荐答案
@Cache（max_hits = 100，超时= 50）通话 __的init __（ max_hits = 100，超时= 50），这样你就不会满足函数参数。
@Cache(max_hits=100, timeout=50) calls __init__(max_hits=100, timeout=50), so you aren't satisfying the function argument.
您可以实现通过该检测功能是否是present的包装方法，你的装饰。如果找到一个函数，它可以返回缓存的对象。否则，它可以返回将被用作装饰包装函数
You could implement your decorator via a wrapper method that detected whether a function was present. If it finds a function, it can return the Cache object. Otherwise, it can return a wrapper function that will be used as the decorator.
class _Cache(object):
def __init__(self, function, max_hits=10, timeout=5):
self.function = function
self.max_hits = max_hits
self.timeout = timeout
self.cache = {}
def __call__(self, *args):
# Here the code returning the correct thing.
# wrap _Cache to allow for deferred calling
def Cache(function=None, max_hits=10, timeout=5):
if function:
return _Cache(function)
else:
def wrapper(function):
return _Cache(function, max_hits, timeout)
return wrapper
@Cache
def double(x):
return x * 2
@Cache(max_hits=100, timeout=50)
def double(x):
return x * 2
这篇关于Python类装饰参数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！