装饰递归函数

Question

我有一个decorator，我写了一个函数的时间。它似乎可以很好地与任何函数一起工作，除了递归函数。在

装饰工：

def tictoc(repeats=3, loops=1):
    def t(func):
        from functools import partial, wraps
        import timeit
        @wraps(func)
        def timer(*args, **kargs):
            elapsed = timeit.repeat(partial(func, *args, **kargs), repeat = repeats, number=loops)
            mine = min(elapsed)
            print "%s finished in %.5fs (%d loops, %d times) with %.5fs per loop" % (func.__name__, mine, loops, repeats, mine/loops)
        return timer
    return t

基本的递归函数是Fibonacci算法。在

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程序失败，错误如下

fib finished in 0.00000s (1 loops, 3 times) with 0.00000s per loop
fib finished in 0.00000s (1 loops, 3 times) with 0.00000s per loop
fib finished in 0.00000s (1 loops, 3 times) with 0.00000s per loop
Traceback (most recent call last):
  File "decor.py", line 61, in <module>
    [fib(x) for x in range(1,50)]
  File "/home/grout/Dropbox/Python/tictoc.py", line 7, in timer
    elapsed = timeit.repeat(partial(func, *args, **kargs), repeat = repeats, number=loops)
  File "/usr/lib/python2.7/timeit.py", line 233, in repeat
    return Timer(stmt, setup, timer).repeat(repeat, number)
  File "/usr/lib/python2.7/timeit.py", line 221, in repeat
    t = self.timeit(number)
  File "/usr/lib/python2.7/timeit.py", line 194, in timeit
    timing = self.inner(it, self.timer)
  File "/usr/lib/python2.7/timeit.py", line 100, in inner
    _func()
  File "decor.py", line 59, in fib
    fib(i-1) + fib(i-2) )
TypeError: unsupported operand type(s) for +: 'NoneType' and 'NoneType'

我不明白decorator是如何执行几次然后失败的。任何帮助都将不胜感激。在

Answer 1

decorator返回的函数不返回任何内容。因此，尽管fib应该返回一个整数，但是被包装的fib返回{}。它可以工作几次，因为一些递归调用是在不检查fib的结果的情况下进行的，但是当它需要结果时（当它必须将两个结果相加时），就会得到异常。在

Answer 2

我想我会解决这个问题的

def tictoc(func, repeats=3, loops=100, *args, **kargs):
    elapsed = timeit.repeat(lambda: func(*args, **kargs), repeat = repeats, number = loops)
    mine = min(elapsed)
    return "%s finished in %.5fs (%s loops, repeated %s times): %.5fs best time per loop"         %(func.__name__, mine, loops, repeats, mine/loops)