Dill/Pickle: Dump custom class object

Question

I am trying to instanciate an object from a custom class, and while doing that to set some class variables, and dump the object. Then, in another file, I want to load the dumped object in order to retrieve the class variables. I will post a small example below:

import dill

class RandomClass:
    mean = 0
    def __init__(self):
        self.name = "random_name"
        self.set_mean(5)

    @classmethod
    def set_mean(cls, value):
        cls.mean = value

obj = RandomClass()
dill.dump(obj, open("test.pkl","wb"))

Then, I want to load the object and retrieve the class variable by doing:

import dill
obj = dill.load(open("test.pkl", "rb"))
obj.mean

However, while doing so, I am getting the following error:

File "/Users/username/Library/Caches/pypoetry/virtualenvs/projectname-py3.6/lib/python3.6/site-packages/dill/_dill.py", line 305, in load obj = pik.load() File "/Users/username/Library/Caches/pypoetry/virtualenvs/projectname-py3.6/lib/python3.6/site-packages/dill/_dill.py", line 577, in _load_type return _reverse_typemap[name]

Looking forward to your answers!

Answer 1

I'm the dill author. I can't reproduce your error. See below ( copy is just dump then load ):

Python 3.6.6 (default, Jun 28 2018, 05:53:46) 
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.39.2)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import dill
>>> class RandomClass:
...   mean = 0
...   def __init__(self):
...     self.name = "random_name"
...     self.set_mean(5)
...   @classmethod
...   def set_mean(cls, value):
...     cls.mean = value
... 
>>> obj = RandomClass()
>>> obj.mean
5
>>> dill.copy(obj)
<__main__.RandomClass object at 0x10747cba8>
>>> 

If your error is persisting, then maybe the best route is to fill out a ticket on the dill GitHub page, and give the version of dill you are using and your OS.