题目

The makeLooper() function (make_looper in Python) takes a string (of non-zero length) as an argument. It returns a function. The function it returns will return successive characters of the string on successive invocations. It will start back at the beginning of the string once it reaches the end.

For example:

abc = make_looper('abc')
abc() # should return 'a' on this first call
abc() # should return 'b' on this second call
abc() # should return 'c' on this third call
abc() # should return 'a' again on this fourth call

我的答案

def make_looper(string):
    global i
    i = -1
    def throw():
        global i
        i += 1
        if i == len(string):
            i = 0
        return string[i]
    return throw

其他精彩答案

from itertools import cycle

def make_looper(s):
    g = cycle(s)
    return lambda: next(g)

from itertools import cycle

class make_looper(cycle):
    
    def __call__(self):
        return self.__next__()

def make_looper(string):
    def generator():
        while True:
            for char in string:
                yield char
    return generator().next