Closing socket file descriptors

[Yang]

Hi, thanks for your answer. Should I just use that object's close() 
method? Is it safe to assume that objects that have fileno() also have 
close()? (Statically typed interfaces would come in handy now.)

I'm writing a simple asynchronous I/O framework (for learning purposes - 
I'm aware of the myriad such frameworks for Python), and I'm writing a 
wrapper around objects that can be passed into select.select(). Since 
select() requires objects that have fileno's, that's the only 
requirement I place on the wrapped object's interface, and thus why I've 
been using FD-based operations:

class handle( object ):
  '''handle( underlying_file ) -> handle object

  A wrapper for a nonblocking file descriptor/handle.  Wraps any object
  with a fileno() method.'''

  __slots__ = [ '_real' ]
  # _real is the underlying file handle.  Must support fileno().

  def __init__( self, real_handle ):
    self._real = real_handle

  def fileno( self ):
    return self._real.fileno()

  def close( self ):
    close( self._real.fileno() )
    # seems that this must now become: self._real.close()

  def wait_readable( self ):
    ...

"js " <ebgssth at gmail.com> wrote in 
news:mailman.7927.1179646552.32031.python-list at python.org:

> Hello, Yang.
> 
> You're not supposed to use os.open there.
> See the doc at http://docs.python.org/lib/os-fd-ops.html
> 
> Is there any reason you want to use os.close?
> 
> On 20 May 2007 04:26:12 GMT, Yang
> <DELETETHISyang.news at mailnulldeletethis.com> wrote:
>> Hi, I'm experiencing a problem when trying to close the file 
descriptor
>> for a socket, creating another socket, and then closing the file
>> descriptor for that second socket. I can't tell if my issue is about
>> Python or POSIX.
>>
>> In the following, the first time through, everything works.  On the
>> second connection, though, the same file descriptor as the first
>> connection may be re-used, but for some reason, trying to do
>> os.read/close on that file descriptor will cause an error.
>>
>> Thanks in advance for any help on why this problem is occurring 
and/or
>> how to resolve it (preferrably, I can continue to use file 
descriptors
>> instead of resorting to socket.recv/socket.close).
>>
>>     def handle( s ):
>>         print id(s), s
>>         print os.read( s.fileno(), 4096 )  # s.recv(4096)
>>         os.close( s.fileno() )  # s.close()
>>     svr = socket.socket()
>>     svr.bind( ( 'localhost', 8003 ) )
>>     svr.listen( 1 )
>>     while True:
>>         print 'accepting'
>>         s,_ = svr.accept()
>>         handle( s )
>>
>> # Traceback (most recent call last):
>> #   File "./normal_server_close_error.py", line 25, in <module>
>> #     handle( s )
>> #   File "./normal_server_close_error.py", line 13, in handle
>> #     print os.read( s.fileno(), 4096 )  # s.recv(4096)
>> # OSError: [Errno 9] Bad file descriptor
>> --
>> http://mail.python.org/mailman/listinfo/python-list
>>
>