Python中的实例变量是否必须在__init__方法中为类初始化？

Question

Why is it if I don't set self.ser = False first, I cannot pass around the self.ser variable as a handle to write with pyserial ?

import serial
import time

class TestClass(object):

    def __init__(self, port='/dev/ttyUSB0', baud=9600):
        self.baud = baud
        self.port = port
        self.ser = False

    def connect(self):
        """Opens serial connection to Device"""
        self.ser = serial.Serial(self.port, self.baud, timeout=.5)

    def writeuart(self, message):
        self.ser.flushInput()
        self.ser.write(message)
        time.sleep(1)
        return self.ser.read(self.ser.inWaiting())

So in other words, can I not create self.ser from within the connect() method and then make use of self.ser in other methods of the same class?

Answer 1

def __init__(self, port='/dev/ttyUSB0', baud=9600):
    self.baud = baud
    self.port = port
    self.connect()       # it's ok