in urllib2, you will find these lines:
        # Wrap the HTTPResponse object in socket's file object adapter
        # for Windows.  That adapter calls recv(), so delegate recv()
        # to read().  This weird wrapping allows the returned object to
        # have readline() and readlines() methods.

        # XXX It might be better to extract the read buffering code
        # out of socket._fileobject() and into a base class.

        r.recv = r.read
        fp = socket._fileobject(r, close=True)

This, storing a bound method in the instance, will cause a reference 
cycle that the user knows nothing about.

I propose creating a wrapper instance with a recv() method instead.  Or, 
is there a standard way of storing bound methods on instances?  A 
'weakmethod', perhaps?

I have two solutions for this problem.  The first is a mundane one, and 
what I employed in our production environment:
class RecvAdapter(object):
    def __init__(self, wrapped):
        self.wrapped = wrapped
    def recv(self, amt):
        return self.wrapped.read(amt)
    def close(self):
        self.wrapped.close()

...
    fp = socket._fileobject(RecvAdapter(r), close=True)


The second solution is a bit more interesting.  It involves applying 
what I call a weakmethod: A bound method that holds a weak ref to the 
object instance:

import weakref
class WeakMethod(object):
    def __init__(self, bound):
        self.weakself = weakref.proxy(bound.im_self)
        self.methodname = bound.im_func.func_name
    def __call__(self, *args, **kw):
        return getattr(self.weakself, self.methodname)(*args, **kw)

We then do:
    r.recv = WeakMethod(r.read)
    fp = socket._fileobject(r, close=True)

I've had many uses for a WeakMethod through the years.  I wonder if such 
a class might be considered useful enough to be put into the weakref 
module.

The WeakMethod idea is not new:

http://code.activestate.com/recipes/81253/

http://mindtrove.info/articles/python-weak-references/#toc-extending-weak-
references

weak method idea seems interesting. I have not used it anytime yet, and
in this case,it seems okay.

cool.  The mindtrove one in particular seems nice.  I didn't realize 
that one could build boundobjects oneself.
Is there any chance of getting a weakmethod class into the weakref 
module?

On Fri, Dec 11, 2009 at 09:40:40AM +0000, Kristján Valur Jónsson wrote:
> Is there any chance of getting a weakmethod class into the weakref 
> module?

This is a separate feature request on weakref module. It may opened
and discussion carried out there?

Lets just investigate the circular reference part here for this ticket.

Does this issue still exist? I did a little poking around at could not find the quoted code.

in python/trunk/Lib/urllib2.py, line 1161

It doesn't appear to be an issue in py3k.