三个Python 小函数

检查是否为ASCII 字符串：

def is_ascii(s):
    return all(ord(c) < 128 for c in s)

 

检查是否为有效的文件名，非常严格的检查仅允许英、数、下划线、减号、点：

def _chk_filename(filename):
    """check filename valid"""
    chars = '^[\-_\.a-zA-Z0-9]*$'
    return re.match(chars, filename)

 
生成随机文件名：

def _rnd_filename(chars=string.hexdigits, length=16, prefix='',
                        suffix='', verify=True, attempts=10):
        for attempt in range(attempts):
            filename = ''.join([random.choice(chars) for i in range(length)])
            filename = prefix + filename + suffix
            if not verify or not os.path.exists(filename):
                return filename