一篇文章帶你弄懂Python異常傳遞和自定義異常

import time
try:    f = open('test.txt')    try:        while True:            content = f.readline()            if len(content) == 0:                break            time.sleep(2)    finally:        f.close()        print('關(guān)閉文件')except :   print("沒有這個(gè)文件")finally:    print("最后的finally")
# 這是test.txt文件中讀取到信息

   def test1():        print("----test1-1----")        print(num)        print("----test1-2----")

    def test2():        print("----test2-1----")        test1()        print("----test2-2----")

    def test3():        try:            print("----test3-1----")            test1()            print("----test3-2----")        except Exception as result:            print("捕獲到了異常，信息是:%s"%result)
        print("----test3-2----")

    test3()    print("------華麗的分割線-----")    test2()

class ShortInputException(Exception):    '''自定義的異常類'''    def __init__(self, length, atleast):        #super().__init__()        self.length = length        self.atleast = atleast
def main():    try:        s = input('請(qǐng)輸入 --> ')        if len(s) < 3:            # raise引發(fā)一個(gè)你定義的異常            raise ShortInputException(len(s), 3) #自定義異常長(zhǎng)度為3。                except ShortInputException as result:#x這個(gè)變量被綁定到了錯(cuò)誤的實(shí)例              print('ShortInputException: 輸入的長(zhǎng)度是 %d,長(zhǎng)度至少應(yīng)是 %d'% (result.length, result.atleast))    else:        print('沒有異常發(fā)生.')
main()

class Test(object):    def __init__(self, switch):        self.switch = switch #開關(guān)    def calc(self, a, b):        try:            return a/b        except Exception as result:            if self.switch:                print("捕獲開啟，已經(jīng)捕獲到了異常，信息如下:")                print(result)            else:                #重新拋出這個(gè)異常，此時(shí)就不會(huì)被這個(gè)異常處理給捕獲到，從而觸發(fā)默認(rèn)的異常處理                raise
a = Test(True)
a.calc(11,0)
print("----------------------華麗的分割線----------------")
a.switch = Falsea.calc(11,0)