which exception catches xxxx error in python

Question

given a traceback error log, i don't always know how to catch a particular exception.

my question is in general, how do i determine which "except" clause to write in order to handle a certain exception.

example 1:

  File "c:\programs\python\lib\httplib.py", line 683, in connect
    raise socket.error, msg
error: (10065, 'No route to host')

example 2:

return codecs.charmap_encode(input,errors,encoding_table)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xd7 in position(...)

catching the 2nd example is obvious:

try:
    ...
except UnicodeDecodeError:
    ...

how do i catch specifically the first error?

Answer 1

Look at the stack trace. The code that raises the exception is: raise socket.error, msg.

So the answer to your question is: You have to catch socket.error.

import socket
...
try:
    ...
except socket.error:
    ...

Answer 2

First one is also obvious, as second one e.g.

>>> try:
...     socket.socket().connect(("0.0.0.0", 0))
... except socket.error:
...     print "socket error!!!"
... 
socket error!!!
>>>