Socket exceptions aren't in the standard exception hierarchy

[John Nagle]

Steve Holden wrote:
> John Nagle wrote:
> 
>> Dennis Lee Bieber wrote:
>>
>>> On Sun, 22 Apr 2007 23:20:25 -0700, John Nagle <nagle at animats.com>
>>> declaimed the following in comp.lang.python:
>>>
>>>
>>>> 2. File "D:\Python24\lib\socket.py", line 295, in read
>>>> data = self._sock.recv(recv_size)
>>>> error: (10054, 'Connection reset by peer')
>>>>
>>>     That looks like M$ Windows version of UNIX/Linux error number 54
>>> (pretty much all Windows socket errors are UNIX number+10000)
>>>
>>>     Errors coming from Windows may not be mapped to specific Python
>>> exceptions, but rather to some general error conditions. {hypothesis} As
>>> such, the Windows errors may not match what UNIX/Linux report.
>>
>>
>>      Actually, that's not what's happening. The socket module is
>> explicitly raising "socket.error" in C code.  It's not an OSError or
>> a WindowsError, although the text makes it look like one.
>>
>>      The problem is not that socket errors aren't entirely portable.
>> It's that they're not even in the Python exception hierarchy.
>> See "http://docs.python.org/lib/module-exceptions.html".
>> They have their own hierarchy, which starts at "socket.error".
>> All built-in exceptions were supposed to be converted to the
>> standard exception hierarchy back before Python 2.0, but these
>> weren't.
>>
>>      Either they should be under IOError, or there should be
>> "NetworkError" under EnvironmentError, and they should be under
>> that.  "NetworkError", alongside IOError in the hierarchy,
>> would be useful.  All the things that go wrong in networking
>> belong under there.  Socket-level errors, SSL/TLS-level errors,
>> and HTTP/FTP/etc. level errors all belong under NetworkError.
>>
>>      This has to be fixed before PEP 352, when the exception
>> hierarchy is enforced, or the socket exceptions won't even work
>> right.
>>
> John:
> 
> Where did you get this information? If true it would certainly need to 
> be logged as a bug, but under Windows on 2,4 I see
> 
>  >>> issubclass(socket.gaierror, Exception)
> True
>  >>>
> 
> and the same under Cygwin 2.5. I am presuming most other users will see 
> the same thing.
> 
> regards
>  Steve

     Ah.  "socket.error" is a subclass of "Exception", but not
of "StandardError".

	 issubclass(socket.error,StandardError)

is False.


					John Nagle