Python3 Exception Handling

What is an exception

Python uses exception objects (Exception object) to represent exception conditions. An exception is thrown when an error is encountered, and if the exception object is not processed or snapped , the program terminates execution with backtracking (traceback) .

Raise statement:

Exceptions can be raised automatically when something goes wrong. There are two ways to throw an exception:

1 . Using a class, it should be a subclass of Excepion (when using a class, the program automatically creates an instance of the class) 2. The instance parameter invokes the raise statement.

Instance (using the built-in exception exception class):

In [1]: raise Exception ---------------------------------------------------------------------------Exception Traceback (most recent call Last)<ipython-input-1-fca2ab0ca76b>inch<module>()---->1raise Exceptionexception: #raise Exception throws a common exception that does not have any information about the error. in [2]:Raise Exception (' The hyperdrive overload ')---------------------------------------------------------------------------Exception Traceback (most recent call Last)<ipython-input-2-3d981203beac>inch<module>()---->1Raise Exception ('The hyperdrive overload') Exception:the hyperdrive overload
#添加了错误信息

Built-in exception class:

There are many built-in exception classes, all in the exceptions module. The official website Manual (3.5.1 version), in 3.5.1+, is integrated into the built-in modules.

Id	Class name	Describe
1	Raise Exception	base class for all exceptions
2	Raise Attributeerror	Thrown when a feature reference or assignment fails
3	Raise IOError	Trying to hit a nonexistent file (including other cases)
4	Raise Indexerror	Use an index that does not exist in the sequence
5	Raise Keyerror	Use a key that does not exist in the map
6	Raise Nameerror	Name not found (variable)
7	Raise SyntaxError	Thrown when the code is in the wrong form
8	Raise TypeError	When a built-in operation or function is applied to an object of the wrong type
9	Raise ValueError	The correct type object, but the object uses an inappropriate value
10	Raise Zerodivisionerror	Division, the second parameter is 0

Custom Exception classes:

Make sure that you inherit from the exception class, either directly or indirectly (can be a subclass of other built-in exception classes), and write a custom exception class as follows:

#!/usr/bin/env python#Encoding:utf-8"""@author: Kamil.liu @file: Exception.py@time:16-5-30 morning 10:56"""#Raise Exception#Raise Attributeerror#Raise IOError#Raise Indexerror#Raise Keyerror#Raise Nameerror#Raise SyntaxError#Raise TypeError#Raise ValueError#Raise Zerodivisionerrorclasskamilexception (Exception):PassPrint(Type (kamilexception))Print(dir (kamilexception))

Results:

/usr/bin/python3.5/home/kamil/pycharmprojects/untitled/test1/exception.py<class 'type'>['__cause__','__class__','__context__','__delattr__','__dict__','__dir__','__doc__','__eq__','__format__','__ge__','__getattribute__','__gt__','__hash__','__init__','__le__','__lt__','__module__','__ne__','__new__','__reduce__','__reduce_ex__','__repr__','__setattr__','__setstate__','__sizeof__','__str__','__subclasshook__','__suppress_context__','__traceback__','__weakref__','args','With_traceback']process finished with exit code 0

Python3 Exception Handling