说明
1、程序可以通过创建一个新的异常类来命名它们自己的异常。异常应该是典型的继承自Exception类,直接或间接的方式。
2、异常python有一个大基类,继承了Exception。因此,我们的定制类也必须继承Exception。
实例
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class ShortInputException(Exception):
def __init__( self , length, atleast):
self .length = length
self .atleast = atleast
def main():
try :
s = input ( '请输入 --> ' )
if len (s) < 3 :
# raise引发一个你定义的异常
raise ShortInputException( len (s), 3 )
except ShortInputException as result: #x这个变量被绑定到了错误的实例
print ( 'ShortInputException: 输入的长度是 %d,长度至少应是 %d' % (result.length, result.atleast))
else :
print ( '没有异常发生' )
main()
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知识点扩展:
自定义异常类型
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#1.用户自定义异常类型,只要该类继承了Exception类即可,至于类的主题内容用户自定义,可参考官方异常类
class TooLongExceptin(Exception):
"this is user's Exception for check the length of name "
def __init__( self ,leng):
self .leng = leng
def __str__( self ):
print ( "姓名长度是" + str ( self .leng) + ",超过长度了" )
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捕捉用户手动抛出的异常
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#1.捕捉用户手动抛出的异常,跟捕捉系统异常方式一样
def name_Test():
try :
name = input ( "enter your naem:" )
if len (name)> 4 :
raise TooLongExceptin( len (name))
else :
print (name)
except TooLongExceptin,e_result: #这里异常类型是用户自定义的
print ( "捕捉到异常了" )
print ( "打印异常信息:" ,e_result)
#调用函数,执行
name_Test()
= = = = = = = = = = 执行结果如下: = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
enter your naem:aaafsdf
捕捉到异常了
Traceback (most recent call last):
打印异常信息: 姓名长度是 7 ,超过长度了
姓名长度是 7 ,超过长度了
File "D:/pythoyworkspace/file_demo/Class_Demo/extion_demo.py" , line 16 , in name_Test
raise TooLongExceptin( len (name))
__main__.TooLongExceptin: <exception str () failed>
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "D:/pythoyworkspace/file_demo/Class_Demo/extion_demo.py" , line 26 , in <module>
name_Test()
File "D:/pythoyworkspace/file_demo/Class_Demo/extion_demo.py" , line 22 , in name_Test
print ( "打印异常信息:" ,e_result)
TypeError: __str__ returned non - string ( type NoneType)
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以上就是python用户自定义异常的实例讲解的详细内容,更多关于python用户如何自定义异常的资料请关注服务器之家其它相关文章!
原文链接:https://www.py.cn/jishu/jichu/31895.html