Pickle Encoding Errors

Dan daniel.maraguirre at googlemail.com
Sun Sep 20 13:59:09 CEST 2009


To demonstrate the problem I have written the following program:

___________________________________  Code Start
________________________________
import pickle

destruct=1

class PickleTest:
	library={}

	def __init__(self):
		self.unpickle()
	def __del__(self):
		if destruct:
			print "Pickling from destructor..."
			self.pickle()

	def unpickle(self):
		try:
			f=open("pickle.txt")
			self.library=pickle.load(f)
			f.close()
			print "Unpickled just fine"
		except:
			print "Error unpickling"
			self.library={u"A": 1,
						  u"B": 2,
						  u"C": 3}

	def pickle(self):
		f=open("pickle.txt","w")
		pickle.dump(self.library,f)
		f.close()
		print "Pickled just fine"

if __name__=="__main__":
	pt=PickleTest()
	if not destruct:
		print "Pickling from __main__..."
		pt.pickle()
___________________________________ Code End
________________________________

Running the program with "pickle.txt" not created and destruct=1
generates the following output:

Error unpickling
Pickling from destructor...
Exception exceptions.LookupError: 'unknown encoding: raw-unicode-
escape' in <bound method PickleTest.__del__ of <__main__.PickleTest
instance at 0xb7d3decc>> ignored

If I now change destruct to 0 the output is:

Error unpickling
Pickling from __main__...
Pickled just fine

Even more odd is that with an existing "pickle.txt" and destruct set
to 1 it seems to work correctly:

Unpickled just fine
Pickling from destructor...
Pickled just fine



I'm running Python 2.5.4 on Debian Sid.

If anybody understands the error please enlighten me.

Dan



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