How to pickle Permutation object

[MichaelALong]

I'm trying to pickle a class instance that contains Permutation objects, and these objects are not unpickling as I expected. Here is code to reproduce what I'm seeing. How do I save and load Permutation objects from disk?

from sympy.combinatorics.perm_groups import Permutation, PermutationGroup
import pickle

perm = Permutation([0,1,2,3,5,4], size=20)
fname = "test.pickle"
output = open(fname, 'wb')
pickle.dump(perm, output)
output.close()
print(perm)

output = open(fname, 'rb')
perm = pickle.load(output)
output.close()
print(perm)

prints:
(19)(4 5)
()

[oscarbenjamin]

When I try this code it seems to work fine:

In [1]: from sympy.combinatorics.perm_groups import Permutation, PermutationGroup
   ...: import pickle
   ...: 
   ...: perm = Permutation([0,1,2,3,5,4], size=20)
   ...: fname = "test.pickle"
   ...: output = open(fname, 'wb')
   ...: pickle.dump(perm, output)
   ...: output.close()
   ...: print(perm)
   ...: 
   ...: output = open(fname, 'rb')
   ...: perm = pickle.load(output)
   ...: output.close()
   ...: print(perm)
(19)(4 5)
(19)(4 5)

[MichaelALong]

Pip says I'm using sympy version 1.12. I also tried after installing sympy 1.11 and 1.08. I get the same result for all these versions. Do you have any ideas what else could be going on?

[oscarbenjamin]

I can reproduce the problem with 1.12. It is fixed on master.