在 Python 中，except: 和 except Exception as e: 之间的区别
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Difference between except: and except Exception as e: in Python
提问by narendranathjoshi
Both the following snippets of code do the same thing. They catch every exception and execute the code in the except:block
以下两个代码片段都做同样的事情。他们捕获每个异常并执行except:块中的代码
Snippet 1 -
片段 1 -
try:
#some code that may throw an exception
except:
#exception handling code
Snippet 2 -
片段 2 -
try:
#some code that may throw an exception
except Exception as e:
#exception handling code
What is exactly the difference in both the constructs?
两种结构的确切区别是什么？
采纳答案by agf
In the second you can access the attributes of the exception object:
在第二个中，您可以访问异常对象的属性：
>>> def catch():
... try:
... asd()
... except Exception as e:
... print e.message, e.args
...
>>> catch()
global name 'asd' is not defined ("global name 'asd' is not defined",)
But it doesn't catch BaseExceptionor the system-exiting exceptions SystemExit, KeyboardInterruptand GeneratorExit:
但它不会捕获BaseException或系统退出异常SystemExit，KeyboardInterrupt并且GeneratorExit：
>>> def catch():
... try:
... raise BaseException()
... except Exception as e:
... print e.message, e.args
...
>>> catch()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 3, in catch
BaseException
Which a bare except does:
其中一个裸除了：
>>> def catch():
... try:
... raise BaseException()
... except:
... pass
...
>>> catch()
>>>
See the Built-in Exceptionssection of the docs and the Errors and Exceptionssection of the tutorial for more info.
回答by Veedrac
except:
accepts allexceptions, whereas
接受所有异常，而
except Exception as e:
only accepts exceptions that you're meantto catch.
只接受例外，你的意思来抓。
Here's an example of one that you're not meant to catch:
下面是一个你不想抓住的例子：
>>> try:
... input()
... except:
... pass
...
>>> try:
... input()
... except Exception as e:
... pass
...
Traceback (most recent call last):
File "<stdin>", line 2, in <module>
KeyboardInterrupt
The first one silenced the KeyboardInterrupt!
第一个沉默了KeyboardInterrupt！
Here's a quick list:
这是一个快速列表：
issubclass(BaseException, BaseException)
#>>> True
issubclass(BaseException, Exception)
#>>> False
issubclass(KeyboardInterrupt, BaseException)
#>>> True
issubclass(KeyboardInterrupt, Exception)
#>>> False
issubclass(SystemExit, BaseException)
#>>> True
issubclass(SystemExit, Exception)
#>>> False
If you want to catch any of those, it's best to do
如果你想抓住其中任何一个，最好这样做
except BaseException:
to point out that you know what you're doing.
指出你知道你在做什么。
Allexceptions stem from BaseException, and those you're meant to catch day-to-day (those that'll be thrown forthe programmer) inherit too from Exception.
所有异常都源自BaseException，而那些您打算每天捕获的异常（将为程序员抛出的异常）也继承自Exception.
回答by Diego Herranz
There are differences with some exceptions, e.g. KeyboardInterrupt.
除了一些例外，例如KeyboardInterrupt 之外，还有一些区别。
Reading PEP8:
阅读PEP8：
A bare except: clause will catch SystemExit and KeyboardInterrupt exceptions, making it harder to interrupt a program with Control-C, and can disguise other problems. If you want to catch all exceptions that signal program errors, use except Exception: (bare except is equivalent to except BaseException:).
一个空的 except: 子句将捕获 SystemExit 和 KeyboardInterrupt 异常，使得用 Control-C 中断程序变得更加困难，并且可以掩盖其他问题。如果要捕获所有表示程序错误的异常，请使用except Exception:（bare except 等价于except BaseException:）。
回答by Silas Ray
Using the second form gives you a variable (named based upon the asclause, in your example e) in the exceptblock scope with the exception object bound to it so you can use the infomration in the exception (type, message, stack trace, etc) to handle the exception in a more specially tailored manor.
使用第二种形式在块范围内为您提供一个变量（as在您的示例中基于子句命名e），except异常对象绑定到它，因此您可以使用异常中的信息（类型、消息、堆栈跟踪等）来在更特别定制的庄园中处理异常。
回答by jouell
Another way to look at this. Check out of the details of the exception:
看待这个问题的另一种方式。查看异常的详细信息：
In [49]: try:
...: open('file.DNE.txt')
...: except Exception as e:
...: print(dir(e))
...:
['__cause__', '__class__', '__context__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__suppress_context__', '__traceback__', 'args', 'characters_written', 'errno', 'filename', 'filename2', 'strerror', 'with_traceback']
There are lots of "things" to access using the 'as e' syntax.
使用“as e”语法可以访问很多“事物”。
This code was solely meant to show the details of this instance.
此代码仅用于显示此实例的详细信息。
