python密码生成器

class Password(object):
    """docstring for Combination"""
    def __init__(self, chas=''.join([chr(j) for j in range(32,127)])):
        super(Combination, self).__init__()
        self.chas = chas
    def straddone(self,string,index=-1):
        chars_len = len(self.chas)
        sting_len = len(string)
        endstr = self.chas[-1]*sting_len
        if string != endstr:
            i = self.chas.index(string[index])
            if i >= chars_len-1:
                i = 0
                arr = list(string)
                arr[index] = self.chas[i]
                string = ''.join(arr)
                index = index - 1
                string = self.straddone(string,index)
            else:
                i = i + 1
                arr = list(string)
                arr[index] = self.chas[i]
                string = ''.join(arr)
        return string
    def generate(self,string=''.join([chr(j) for j in range(32,127)])):
        self.chas = string
        string_len = len(string)
        for i in range(string_len):
            start_string = self.chas[0]*(i+1)
            end_string = self.chas[-1]*(i+1)
            while start_string != end_string:
                print(start_string)
                start_string = self.straddone(start_string)