On 04/27, Chris Angelico wrote: > On Mon, Apr 27, 2015 at 2:24 PM, Ethan Furman wrote: > > On 04/27, Makoto Kuwata wrote: > >> > >> I feel that function decorator having arguments is complicated, > >> because three 'def' are nested: > >> > >> def multiply(n): > >> def deco(func): > >> def newfunc(*args, **kwargs): > >> return n * func(*args, **kwargs) > >> return newfunc > >> return deco > > > > When I have to write an argument-taking decorator, I use a class: > > > > class multiply(object): # don't need 'object in 3.x' > > > > def __init__(self, n): > > self.n = n > > > > def __call__(self, func): > > def newfunc(*args, **kwargs): > > return self.n * func(*args, **kwargs) > > return newfunc > > What's the advantage of that over a simple closure? You have the same > number of nesting levels, plus a lot more boiler-plate repetition - > instead of just referencing names from the outer scope, you have to > explicitly capture them all with "self.n=n" for each one. I'm not sure > you really even gain much clarity. > > In a way, a closure is a short-hand for an object with a __call__ > method that auto-captures all its local variables.
I find it much easier to keep track of what is going on, especially in those cases where there is pre-, post-, or both, processing going on. YMMV. -- ~Ethan~ -- https://mail.python.org/mailman/listinfo/python-list
