Python 装饰器函数 wraps 利用缓存查询原理，加速递归

# 装饰器函数
def foo(fn):
    def wrappers():
        print("hello, %s" %fn.__name__)
        fn()
        print("bye, %s" %fn.__name__)
    return wrappers
    
@foo
def fooo():
    print("i am fooo")

fooo()
    
from functools import wraps
import time
def demof(fn):
    cache={}
    miss=object()
    @wraps(fn)
    def www(*args):
        result=cache.get(args,miss)
        if result is miss:
            result=fn(*args)
            cache[args]=result
        return result
    return www

@demof
def fib(n):
    if n<2:
        return n
    return fib(n-1)+fib(n-2)
st=time.time()
for i in range(3,30):
     fib(i)
     
se=time.time()
print(se-st)


def fib1(n):
    if n<2:
        return n
    return fib1(n-1)+fib1(n-2)

st=time.time()
for i in range(3,30):
    fib1(i)

se=time.time()
print(se-st)



def dumpstep(fn):
    cache={}
    miss=object()
    @wraps(fn)
    def wwww(*args):
        result=cache.get(args,miss)
        if result is miss:
            result=fn(*args)
            cache[args]=result
        return result
    return wwww

@dumpstep
def Step(n):
    if n<2:
        return 1
    if n<3:
        return 2
    return Step(n-1)+Step(n-2)

for i in range(1,100):
    print(Step(i),end=" , ")
    if i%10==0:
        print("\n")