New submission from HwidongNa le...@postech.ac.kr:
I'm trying to pickle a class instance containing two lists of another
instances. The instances in the two lists have attributes that refer instances
of each other. Here are the classes.
import pickle
from copy import copy
class Graph:
def __init__(self):
self.vertices = {}
self.edges = set()
def __repr__(self):
return \n.join(map(str, sorted(self.vertices, key=lambda v:v.id)))
class Edge:
def __init__(self, vfrom, vto):
self.vfrom = vfrom
self.vto = vto
def __hash__(self):
return hash((self.vto, self.vfrom))
def __repr__(self):
return str(self.vto.id)
def __getstate__(self):
vfrom = copy(self.vfrom)
vfrom.del_outgoing(self)
vto = copy(self.vto)
vto.del_incoming(self)
self.__dict__.update({vfrom:vfrom, vto:vto, })
return self.__dict__
def __setstate__(self, state):
self.__dict__.update(state)
self.__dict__[vfrom].add_outgoing(self)
self.__dict__[vto].add_incoming(self)
class Vertex:
def __init__(self, id):
self.id = id
self.incoming = set()
self.outgoing = set()
def __repr__(self):
return Vertex %d - %s%(self.id, , .join(map(str, self.outgoing)))
def __hash__(self):
return hash(self.id)
def add_incoming(self, edge):
if not edge in self.incoming:
self.incoming.add(edge)
def add_outgoing(self, edge):
if not edge in self.outgoing:
self.outgoing.add(edge)
def del_incoming(self, edge):
self.incoming.discard(edge)
def del_outgoing(self, edge):
self.outgoing.discard(edge)
I got an AssertionError when I pickled a simple graph as follows.
v0 = Vertex(0)
v1 = Vertex(1)
e0to1 = Edge(v0, v1)
v0.add_outgoing(e0to1)
v1.add_incoming(e0to1)
g = Graph()
g.vertices[v0] = v0
g.vertices[v1] = v1
g.edges.add(e0to1)
g.edges.add(e0to1)
v2 = Vertex(2)
e0to2 = Edge(v0, v2)
v0.add_outgoing(e0to2)
v2.add_incoming(e0to2)
g.vertices[v2] = v2
g.edges.add(e0to2)
print g
Vertex 0 - 2, 1
Vertex 1 -
Vertex 2 -
p = pickle.dumps(g)
Traceback (most recent call last):
File stdin, line 1, in module
File /usr/lib/python2.6/pickle.py, line 1366, in dumps
Pickler(file, protocol).dump(obj)
File /usr/lib/python2.6/pickle.py, line 224, in dump
self.save(obj)
File /usr/lib/python2.6/pickle.py, line 286, in save
f(self, obj) # Call unbound method with explicit self
File /usr/lib/python2.6/pickle.py, line 725, in save_inst
save(stuff)
File /usr/lib/python2.6/pickle.py, line 286, in save
f(self, obj) # Call unbound method with explicit self
File /usr/lib/python2.6/pickle.py, line 649, in save_dict
self._batch_setitems(obj.iteritems())
File /usr/lib/python2.6/pickle.py, line 663, in _batch_setitems
save(v)
File /usr/lib/python2.6/pickle.py, line 331, in save
self.save_reduce(obj=obj, *rv)
File /usr/lib/python2.6/pickle.py, line 401, in save_reduce
save(args)
File /usr/lib/python2.6/pickle.py, line 286, in save
f(self, obj) # Call unbound method with explicit self
File /usr/lib/python2.6/pickle.py, line 562, in save_tuple
save(element)
File /usr/lib/python2.6/pickle.py, line 286, in save
f(self, obj) # Call unbound method with explicit self
File /usr/lib/python2.6/pickle.py, line 600, in save_list
self._batch_appends(iter(obj))
File /usr/lib/python2.6/pickle.py, line 615, in _batch_appends
save(x)
File /usr/lib/python2.6/pickle.py, line 286, in save
f(self, obj) # Call unbound method with explicit self
File /usr/lib/python2.6/pickle.py, line 725, in save_inst
save(stuff)
File /usr/lib/python2.6/pickle.py, line 286, in save
f(self, obj) # Call unbound method with explicit self
File /usr/lib/python2.6/pickle.py, line 649, in save_dict
self._batch_setitems(obj.iteritems())
File /usr/lib/python2.6/pickle.py, line 663, in _batch_setitems
save(v)
File /usr/lib/python2.6/pickle.py, line 286, in save
f(self, obj) # Call unbound method with explicit self
File /usr/lib/python2.6/pickle.py, line 725, in save_inst
save(stuff)
File /usr/lib/python2.6/pickle.py, line 286, in save
f(self, obj) # Call unbound method with explicit self
File /usr/lib/python2.6/pickle.py, line 649, in save_dict
self._batch_setitems(obj.iteritems())
File /usr/lib/python2.6/pickle.py, line 663, in _batch_setitems
save(v)
File /usr/lib/python2.6/pickle.py, line 331, in save
self.save_reduce(obj=obj, *rv)
File /usr/lib/python2.6/pickle.py, line 405, in save_reduce
self.memoize(obj)
File /usr/lib/python2.6/pickle.py, line 244, in memoize
assert id(obj) not in self.memo
AssertionError
I worked when the v2 is removed.
v0 = Vertex(0)
v1 = Vertex(1)
e0to1 = Edge(v0, v1)
v0.outgoing.add(e0to1)
v1.incoming.add(e0to1)
g = Graph()
g.vertices[v0] = v0
g.vertices[v1] = v1
