_io.py 文件源码

def __init__(self, raw, buffer_size=DEFAULT_BUFFER_SIZE):
        if not raw.writable():
            raise IOError('"raw" argument must be writable.')

        _BufferedIOMixin.__init__(self, raw)
        if buffer_size <= 0:
            raise ValueError("invalid buffer size")
        self.buffer_size = buffer_size
        self._write_buf = bytearray()
        self._write_lock = Lock()