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POWhy am I getting an error about my class defining __slots__ when trying to pickle an object?
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  1. POWhy am I getting an error about my class defining __slots__ when trying to pickle an object?
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    copied!<p>I'm trying to pickle an object of a (new-style) class I defined. But I'm getting the following error:</p> <pre><code>&gt;&gt;&gt; with open('temp/connection.pickle','w') as f: ... pickle.dump(c,f) ... Traceback (most recent call last): File "&lt;stdin&gt;", line 2, in &lt;module&gt; File "/usr/lib/python2.5/pickle.py", line 1362, in dump Pickler(file, protocol).dump(obj) File "/usr/lib/python2.5/pickle.py", line 224, in dump self.save(obj) File "/usr/lib/python2.5/pickle.py", line 331, in save self.save_reduce(obj=obj, *rv) File "/usr/lib/python2.5/pickle.py", line 419, in save_reduce save(state) File "/usr/lib/python2.5/pickle.py", line 286, in save f(self, obj) # Call unbound method with explicit self File "/usr/lib/python2.5/pickle.py", line 649, in save_dict self._batch_setitems(obj.iteritems()) File "/usr/lib/python2.5/pickle.py", line 663, in _batch_setitems save(v) File "/usr/lib/python2.5/pickle.py", line 306, in save rv = reduce(self.proto) File "/usr/lib/python2.5/copy_reg.py", line 76, in _reduce_ex raise TypeError("a class that defines __slots__ without " TypeError: a class that defines __slots__ without defining __getstate__ cannot be pickled </code></pre> <p>I didn't explicitly define <code>__slots__</code> in my class. Did something I do implicitly define it? How do I work around this? Do I need to define <code>__getstate__</code>?</p> <p><strong>Update:</strong> <a href="https://stackoverflow.com/users/174728/gnibbler">gnibbler</a> chose a good example. The class of the object I'm trying to pickle wraps a socket. (It occurs to me now that) sockets define <code>__slots__</code> and not <code>__getstate__</code> for good reason. I assume once a process ends, another process can't unpickle and use the previous process's socket connection. So while I'm accepting <a href="https://stackoverflow.com/users/95810/alex-martelli">Alex Martelli</a>'s excellent answer, I'm going to have to pursue a different strategy than pickling to "share" the object reference.</p>
 

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